Roger Smith

Table 3: Warmest weeks by daily mean temperatures Part three of the NYC "hot week" study analyzing the top averages on a year by year basis. As with the highs where I reported in more detail, consecutive values for 3-4 days (representing 9-10 days elapsed time) may be quite similar. This list ranks the years by top daily values only. Then it compares the sample of years to those identified as hottest daytime and warmest overnight. In the table below, entry "a" refers to the rank of the same year in average 7d maximum and minimum temps, and entry "b" refers to the day shift (if any) between the seven day intervals involved (for mean and max only). A positive number in "b" means that the mean temp max occurred that number of days later than the avg max, and a negative means that it occurred earlier. Zero means that it was the same seven day interval. Where either statistic was on more than one day, the best fit is used but an asterisk will be added. As an example of how to read the table, 1993 (avg 87.43) has the highest seven day mean and also the third highest ranked average maximum and tied 11th warmest minimum (a). The two intervals were concurrent (with reference to the first part of the study, that interval is identified as July 7-13). If b had been entered as "1" then the reference would be to 8-14 July for the mean temperature. If a year failed to make top 48 in mean max or mean min, that entry would read blank or --- . The first example of that is 1991 (t12) which did not register a top 48 7-day average min and the value of 73.57 was a degree lower than 48th ranked values. Two cases are noted (1980, 1999) where the highest average minimum was in a different heat wave than the highest average max. It probably happens more frequently in average and cooler than average summers. Even when the mean max and the mean daily align, the mean minimum peak may be displaced. This is why 2010 came in with a slightly lower mean than 1980 even though its ranks were both slightly better. The relevant ranked mean minimum was displaced one day later. Rank ____ Avg ____ Year ____ a _______ b ________ Rank ___ Avg _____ Year ____ a ______ b _01 _____ 87.43 ___ 1993 ___ 3, t11 ___ 0 _________ 26 ____ 84.43 ___ 1911 ___25, t29 __0 _02 _____ 87.36 ___ 1977 ___ 1, t20 ___ 0 _________ 27 ____ 84.14 ___ 1917 ___t31, t29__0 _03 _____ 87.14 ___ 1953 ___ 2, t16 ___ 0* ________t28 ____ 84.07 ___ 1885 __ t39, t16 __4 _04 _____ 87.07 ___ 1896 ___t13, 2 ___ 0 _________ t28 ____ 84.07 ___ 1898 __ -----, t13 __0 ^^ _05 _____ 86.86 ___ 2013 ___ 23, 1 ___ 1 __________t30 ____ 84.00 ___ 1892 __ t31, t29__ 1 _06 _____ 86.79 ___ 2011 ___ t7, 4 ___ 0* _________ t30 ____ 84.00 ___ 2016 __ ----, t11 __ 1^^ _07 _____ 86.64 ___ 1988 ___ t11, 3 __ 0 __________ 32 ____ 83.86 ___ 1949 __ t44, -----__ 0 _08 _____ 85.86 ___ 1944 ___ 5, t37___1 __________ t33____ 83.79 ___ 1876 __ t49, t25 __ 1 _09 _____ 85.71 ___ 1955 ___ 6, t29 __ 0 __________ t33 ____83.79 ___ 1961 __ t44, t29 __ 0 _10 _____ 85.57 ___ 2001 ___ t11, 24__ 0 __________ t33 ____ 83.79 ___ 1984 __ t39, t42 __ 0 _11 _____ 85.50 ___ 1980 __ t20, t22^_ 0 __________t36 ____83.64 ___ 1982 __ t53, t29 __ 0 t12 _____ 85.43 ___ 1973 ___ t7, t37 __ 0 __________t36 ____83.64 ___ 2018 __ ----, t29 __ 0 t12 _____ 85.43 ___ 1981 ___24, t13 __ 0 __________ 38 ____ 83.57___ 1940 __ t26, ---- __ 0 t12 _____ 85.43 ___ 1991 ___ 4, --- ___ 0 __________t39 ____ 83.50___ 1872 __ t31, ---- __ 0 _15 _____ 85.36 ___ 2010 __ t13, t16__ 0 __________ t39 ____83.50___ 2005 __ t44, t29 ___ 1 _16 _____ 85.29 ___ 2002 __ t22, t20 __0 __________t41 ____ 83.43___ 1937 __ 28, ---- ___ 0 _17 _____ 85.21^___1999 __ ---- 6 ____ 0 __________t41 ____ 83.43 ___ 1972 __ ----, t27 ___-1 _18 _____ 85.14 ___ 1948 __ t15, t29 _ 0 __________t43 ____ 83.36 ___ 1905 __ ----, t8 ____ -5 t19 _____ 84.93 ___ 1901 ___10, t46 __0 __________t43 ____ 83.36 ___ 1908 __ -----, 5 ____ 0 t19 _____ 84.93 ___ 1983 __ t15, t42__ 0 __________t43 ____ 83.36 ___ 1936 __ t20, --- ___ 0 t19 _____ 84.93 ___ 1995 __ t29, 15 __ 0 __________ 46 ____ 83.21 ___ 1943 ___ t29, --- ___ 0 t22 _____ 84.79 ___ 1952 __ t31, t16 _ 0 __________t47 ____ 83.07 ___ 1925 ___ t15, --- ___ 0 t22 _____ 84.79^___ 1966 __ t7, ---- __ 1 __________t47 ____ 83.07___ 2008 ____t37, --- ___ 1 _24 _____ 84.71 ___ 2006 __ t49, 7 ___ 0 _________ 49 ____ 82.86 ___ 1979 ____----, t22 ___-4 _25 _____ 84.50 ___ 1933 __ t15, --- __0 __________ 50 ____ 82.71 ___ 1906 ____ ----, t8 ____ 0 ___________ (min for 1933 74.0, about 0.5 below 48th) ____^^ 1898 mean max 91.14, all peaks Aug 31 to Sept 6 1898 ______________ (min for 1923 in 31st also 74.0) ______________^^ 2016 was similar, max 91.14, mean peak Aug 11-17 2016 _________________________________________________________________________ * Highest mean for 1953 is same as second of two tied intervals for high max (that ending Sept 3). The value for Sept 2 is marginally lower. * Highest mean for 2011 also same as second of two tied intervals for high max (that ending July 27). ^ For the 1980 entry, the mean min for the heat wave with the average shown (July) was slightly lower than a second heat wave with a lower average max. For the heat wave noted, the mean min was 76.14 which ranks t22nd, but for a second heat wave in August which had a mean of 85.00 (Aug 5-11), the average min was 77.00 (also Aug 5-11) and the peak average max 93.57 (Aug 3-9) so the displacement for this one was 2 days, the ranks of the mean max and mean min were t29, 10. In 2002, the earlier noted portion had a mean of 84.79, slightly lower than the peak heat wave, and the minimum of 75.14 was likewise about a degree lower than the peak heat wave recorded. ^ For the 1999 entry, the highest mean occurred in a separate non-qualifying (for mean max) heat wave 22-23 days before tied peaks for mean max later in the summer. The non-qualifying mean max for the overall mean shown was 93.00. This one combined with the 6th highest average minimum of 77.00. After three weeks of less prolific heat, a second heat wave set the qualifying 95.00 peak (t15th warmest) on two consecutive days (for seven day averages) but with that heat wave the corresponding mean min was 74.71 which ranks t45 with otherwise untied 1870 (about t47 for separate heat waves). So 1999 set the 15th warmest mean max and 6th warmest mean min, although three weeks apart, and had two ranking heat waves for mean temperature if that were the criteria for counting. ^ For the 1966 entry, the highest min was slightly lower than 48th. A later portion of the extended heat wave as noted had a slightly lower value of mean minimum attached also. The mean for the second interval was 83.57 which was 1.22 below the main peak ten days earlier. This is not considered to be a separate heat wave but an extended portion of the qualifying case. (notes about secondary peaks, in 1955 the earlier July sub-peak had a mean of 85.29 (zero days displacement relative to mean max) -- this would rank as 23rd highest heat wave mean temp and would combine equivalent t10 mean daytime max with equivalent t37 mean min (almost equal to the later main entry heat wave), in 1953 the July heat wave (listed as 2b for mean max) had a mean of 83.50 displaced one day later than the mean max peak, and a mean minimum of 73.43 which would rank outside the top 48 by about one degree, while in 1988 the earlier July sub-peak had a mean of 82.79 five days after the mean max peak showing the longevity of that heat wave). This one would rank t27 for heat wave mean max, and its mean minimum finished well outside the top 48. The heat waves of 1905 to 1908 and also 1979 generally levelled off near 88-90F and had warmer ranked overnight lows in the 75-77 range, for unusually small diurnal ranges. This may indicate frequent sea breeze modification, or cloudiness. _________________________________________ ANALYSIS of the frequency of hot average daily temp 7d intervals This shows the ranks of each member of the five intervals in the study ... ranks of mean max and mean min in brackets. Almost all the heat waves produced overlapping intervals of peak mean max and mean min, sometimes there was a one-day lag and in a few cases longer displacements. The greater the displacement, the more the apparent error in the rank attained by the year's highest mean daily (since it has not been derived precisely from these ranked components). Two cases required that two heat waves during the year be re-ranked from the annual rankings as the high min and high max were in two different heat waves. In both cases the differentials are rather small and explained in the text above. 1980 is the highest ranked heat wave to have its mean minimum finish second to another heat wave during the summer (that one while cooler for max temps ranked 10th overall for mean min, its max component ranked the same as 29th annually). n __ interval __ cases 6 __ 1869-1900 _ 1896 4th (t13, 2), 1885 t28 (t39, t16 ), 1898 t28 (---, t13), 1892 t30 (t31, t29), ____ 1876 t33 (t49, t25), 1872 t39 (t31, ---) 7 __ 1901-1930 _ 1901 t19 (10, t46), 1911 26th (25, t29), 1917 27th (t31, t29), 1905, t43 (---, t8), _____ 1908, t43 (---, 5), 1925, t47 (t15, ---), 1906 50th (---, t8). 11 _ 1931-1960 _ 1953 3rd (2, t16), 1944 8th (5, t37), 1955 9th (6, t29), 1948 18th (t15, t29), 1952 t22 (t31, t16), _____1933 25th (t15, ---), 1949 32nd (t44, ---), 1940 38th (t26, ---), 1937 t41 (---, t27), 1936 t43 (t20, ---), 1943 46th (t29, ---). 12 _ 1961-1990 _ 1977 2nd (1, t20), 1988 7th (t11, 3), 1980 11th (t20, t22), 1973 t12 (t7, t37), 1981 t12 (24, t13), 1983 t19 (t15, t42), _____1966 t22 (t7, ---), 1961 t33 (t44, t29), 1984 t33 (t39, t42), 1982 t36 (t53, t29), 1972 t41 (---, t27), 1979 49th (---, t22). 15 _ 1991-2020 _ 1993 1st (3, t11), 2013 5th (23, 1), 2011 6th (t7, 4), 2001 10th (t11, 24), 1991 t12 (4, ---), _____ 2010 15th (t13, t16), 2002 16th (t22, t20), 1999 17th (----, 6), 1995 t19 (t29, 15), 2006 24th (t49, 7), ______2016 t30 (---, t11), 2018 t36 (--- t29), 2005 t39 (t44, t29), 2008 t47 (t37, ----). ______________________________________________________________ The pace of these top 50 heat waves (average temp) has been gradually increasing but of the 15 in the most recent 30 years, about one-third are included mostly for their unusually warm nights. This was also the case in the earliest interval. The daytime highs dominated most around 1931-60.

This thread will track the warmest and coldest weeks in the NYC temperature history 1869 to present. I have worked all of that up in an excel file based on the NYC temperature record (daily) kindly provided to me by Don Sutherland about a year ago. Before I start posting those (which I plan to do in a timely fashion about once a week around weekends), here's the results of a study that I posted in another thread to illustrate changes in the historical frequency of warmest summer weekly intervals, both for daytime highs and overnight lows (and then daily means). Unfortunately the forum just changed its format and some of these tables are not as well aligned as they were before the change. Also if you have that sidebar feature working, the remaining posted material is too narrow, so I am going to edit these tables until I think they are more readable. Let me know what you're seeing. Table 1: Top Fifty NYC Hot weeks (average daytime highs), Annual Basis with noted second heat waves in a few summers This table lists the top 50 heat waves which takes us through the top 48 annual basis weekly extremes, and with the consecutive overlapping weeks that exist within prolonged heat waves, the count is 91 hot intervals of seven days that average 94.0, providing the top 25 years and top 27 heat waves as two years have two heat waves that qualified. This will be followed by warmest overnight lows in a less complex format, and highest mean daily temperatures on a weekly time scale. In the list that follows, you'll see a number of weekly averages with a peak value highlighted. The other intervals shown are on either side of that peak, which is identified in the first part of each entry. For example, the top heat wave in 1977 peaked July 15-21 at 98.43 (avg max) but was above 94 for a total of six intervals which by counting back or forward you can see began with July 13-19, and ended with July 18-24. Then after the specific values, a list of ranks (in the top 91 values in the data set) are given. So the 1977 heat wave includes values that are tied 10th, tied 12th, first, tied 5th, tied 22nd and tied 50th. A summary at the end tells you that this was a heat wave that produced a 12-day interval of six consecutive hot weeks that each averaged over 94.0 F. One or two cases in the table have a few outlying days with almost as hot intervals separating them, and these are considered to be prolonged heat waves rather than secondary or detached second heat waves. But then scrolling down to near 22nd place you'll find heat wave 2b which is 1953's second qualifying heat wave, that was six weeks before the main qualifier, second hottest late August to early September. A more complex situation developed for 1966 and 2002 with extended heat waves but pushing the limits of being separated enough to qualify as two. Then after exhausting all cases with at least one weekly interval of 94.0 (with the 1911 heat wave which managed to peak at that value), I completed the list with 26th to 48th ranked peak weekly values that dropped down through the 93s into the 92s. Now these are not to be taken as an extension of the frequency of such intervals in all data because the hotter years that are tracked from rank 1 to 25 will contain quite a few more of values comparable to these secondary heat wave summers. But this does provide a complete list of the 50 warmest summers as seen from the perspective of mean daily maximum temperatures. That can then later be compared to a similar list for 50 top overnight low averages (see table 2 further down the post). The ranking in the following table is based solely on the value of the highest seven-day mean, and that interval defines the duration specified. Values in brackets on either side of the maximum value are seven-day averages for other intervals that exceed 94.0. For example, the 1977 heat wave peaked July 15-21 at 98.43F. Its rank of all seven-day intervals (shown after the values) is first. Starting July 13-19, various other intervals with averages of 94.0 or above are listed in brackets, and their ranks in the overall list can be seen in the string of rankings (July 13-19 at 96.86 ranked t10). Some notes are added to join together not quite consecutive strings due to a few intervening averages below 94.0 (but still well into the low 90s). For instance, in entry 6 for 1955, July 17-23 averaged 95.43, all intervals July 18-24 to July 30-Aug 5 had averages below 94, then the qualifying values were observed again July 31-Aug 6 to Aug 2-8. As Aug 1-7 had the highest of all these averages (96.14, rank 20) it anchors the table entry. The duration of the heat waves has no bearing on the rankings although it tends to vary at a high correlation to the rankings. ranks of hottest mean daily max (with consecutive 94+) __ ranks of all noted weekly intervals (consecutive) 1. July 15-21 1977 _ (96.86) (96.71) 98.43 (97.29) (95.71)(94.71) _ t10 t12 1 t5 t22 t50 ___ 12 days covered by 6 intervals 2. Aug 27*-Sep 2* 1953 _ (94.57)(95.86)(96.71) 98.29 98.29 (97.14)(95.29) _ t53 21 t12 t2 t2 7 t31___ 13 days covered by 7 intervals 3. July 7-13, 1993 __(96.29)(96.57)(97.00) 98.00 (97.00)(95.57)(94.00) ___19 t14 t8 4 t8 28 t83____ 13 days covered by 7 intervals 4. July 17-23, 1991 _ (94.71) (96.57) (96.43) 97.29 (96.43) __ t50 t14 t17 t5 t17 _____ 11 days covered by 5 intervals 5. Aug 10-16 1944 _ (94.29) (95.71) 96.86 (96.57) (94.14) __t66 t22 t10 t14 t78 __ 11 days covered by 5 intervals 6. July 17-23 and Aug 1-7 1955 __ (94.00) 95.43 ... ... (95.00) 96.14 (94.00) ___ two hot spells with only slight cooling between them ___________________________________ t83 t29 _____________t37, 20, t83 _________ 8d 2int, 13d separated then 9 d covered by 3 intervals t7. June 27 - July 3 1966 _ 95.71 (95.29) (94.57) (94.43) (94.29) (94.86) _ t22^ t31 t53 t59 t67 t47 __ 4d 91-93 then July 7-9 ... ___ July 8-14 (94.29) 94.57 (94.14) ___ t67 t53 t78 ___w4 more d 90-93 _ 18 or 22 days covered by 9 intervals and 7 nearly as hot ____ ____ _____ _____ ______ _______ _____ _____ ____ ____ ___ ___ also six days before the first interval 91-92F avg (total 28d) t7. Aug 28 - Sep 3 1973 __ (94.57) 95.71 (95.00) ______ t53 t22* t37 ________ 9 days covered by 3 intervals (93.86 values at each end) t7. July 17/18-23/24 2011 (94.29) 95.71 95.71 ________t67 t22* t22* _______ 9 days covered by 3 intervals 10. June 27 - July 3 1901 _ (95.00) 95.43 _____________ t37 t29^^ ___________ see note (extended but not as intense) t11. Aug 9-15 1988 _(94.00) 95.29 (94.29) ____________ t83, t31, t67 __ an earlier hot spell peaked at 93.57 July 5-11 t11. Aug 4-10 2001 ________95.29 (94.14) _____________t31 t78 _____________ 8 days covered by 2 intervals t13. Aug 5-11 1896 _ (94.29) 95.14 (95.00) (94.71) ____t67 t35 t37 t50 _____10 days covered by 4 intervals t13. July 3-9 2010 __ (94.00) 95.14 (94.29) (94.00) _____t83 t35 t67 t83 _____10 days covered by 4 intervals t15. June 1-7 1925 ______ 95.00 _______________________t37** _______________ see note t15. July 28 - Aug 3 1933 _(94.43) 95.00 ______________ t60 t37 _________________8 days covered by 2 intervals t15. Aug 24-30 1948 _____(94.43) 95.00 (94.57) _______t60 t37 t53 _____________ 9 days covered by 3 intervals ___ ____ _____ ______ ________ _________ _____________ ________ ______ ____ ____ __ Toronto avg 95 F (Aug 23-29) t15. July 12-18 1983 _____ 95.00 (94.00) ______________ t37 t83 ________________ 8 days covered by 2 intervals t15. July 23/24-29/30 1999 __ 95.00 95.00 (94.00) (94.14) _ t37 t37 t83 t78 ___ 10 days covered by 4 intervals t20. July 8-14 1936 _(94.29) (94.43) 94.86 ____________t67 t60 t47 _____________ this was Toronto's hottest week (99.29) t20. July 16-22, 1980 _ (94.43) 94.86 _________________ t60 t47 ___ (a second hot spell averaged 93.57 Aug 3-9). t22. July 29 - Aug 4, Aug 12-18 2002 _ (94.43) ... (94.29) 94.57 (94.29) _ t60 ... t67 t53 t67 __ entered as one (slight inter- cooling) 23. July 14-20 2013 _______ 94.57 (94.43) _____________t53 t60 __ note this is the most recent entry before 30th 2b July 15-21 1953 _______ 94.43 ____________________ t60 ______ separate event from late Aug-Sept 1953, which ranked 2. 24. July 7-13 1981 ________ 94.14 _____________________t78 25. July 1-7 1911 _________ 94.00 _____________________ t83 ________________ Toronto avg 98 July 1-6 (after this point in the list, I have added years ranked 26 to 48 to provide a similar data base to the minimum temperature analysis posted later in the thread ... these are not entirely heat waves 24 to 48 in rank order because as noted above, a few years produced two or even three non-qualifying separate heat waves that would insert themselves into this list. But the maximum values above can be read in the same way as the rank ordered (1-25) highest seven-day average minima.) The numerous ties are created by the math of dividing whole number totals by seven, there can only be seven rounded two-decimal outcomes (.00, .14, .29, .43, .57, .71, .86). This list shows the second heat waves in 1988 and 1980 noted above but does not include them in the rank numbering system (if you wanted to convert to a list of heat waves then add one to each rank number below a second heat wave note). xx. __ 93.86 ___ (none) t26. __ 93.71 ___ 1940, 1949 ___ also 2nd 1988 heat wave July 5-11 (heat wave 30) __ 93.57 ___ (none) ____ also 2nd 1980 heat wave Aug 3-9 (add 3 to ranks if counting heat waves and not years, the additional ones include 1953 "2b" and 1988, 1980 above) 28. __ 93.43 ___ 1937 t29. __ 93.29 ___ 1943, 1995 t31. __ 93.14 ___ 1872, 1892, 1917, 1952, 1964, 2016 xx. __ 93.00 ___ none t37. __ 92.86 ___ 1957, 2008 t39. __ 92.71 ___ 1885, 1984 t41. __ 92.57 ___ 1954, 1963, 2012 44. __ 92.43 ___ 2022 t45. __ 92.29 ___ 1923, 1924, 1941, 1961, 2005 (also in top 50 ...) t50. __ 92.14 ___ 1876, 1919, 1997, 2006 (also Aug 3-9 2022, not highest of year see 44 above) ... note that in Aug 1918, seven days in a 10d span Aug 5-14 averaged 95, but a 71F max midway through left this two-part heat wave (with the all-time Aug record of 104F) on the sidelines. ... ... ... the warmest week 2017 to 2022 was 91.57 June 29-July 5, 2018 until 92.43 became the new high July 19-25 2022. . ... ... ... the average for all years 1869 to 2020 is 90.8. For 1869-1900 it was 89.3, for 1901-60 it was also 90.8, and for 1961-90, 1991-2020 both halves had identical 91.6 averages. (for clarity, this is the average of the warmest 7d interval of each year). (note the coldest weeks have warmed up more, the same stats for that are 1869-2020 27.15, 1869-1900 24.2, 1901-60 28.0, 1961-90 26.7 1991-2020 29.2) Just as a basis for discussion, these stats are consistent with an urban heat island increasing by 1 F deg in summer to the 1930s and another 1 F to present day assuming a levelling off after 1980. If you think that estimate of the u.h.i. for NYC is too large then the amount by which you estimate the u.h.i. leaves a trace of some other process at work (some combination of natural warming and AGW). The winter or coldest week stats are consistent with an urban heat island increase about twice as large with evidence of a colder turn around the 1960s to 1980s and signs of a further warming recently that would more likely be from some factor unconnected to the heat island. (I will probably post this summary closer to the winter) _____________________________________________________________ * same value Aug 28 - Sep 3 1953 ... Aug 28 to Sep 3 1973 average was 95.71 ranked t22. ^ This heat wave took top spot for all weeks from the one indicated to July 2-8, but values were lower than 20th (near 95 F). ^^ The 1901 value shown was second highest for that weekly interval but took top spots for the two previous intervals which were 92.57 and 95.00. ** The 1925 early June heat wave took top spots for weeks ending June 5 to 10, the other values were all in the range of 90 to 93. ====================================================== ANALYSIS _ There were 25 qualifying heat waves with at least one seven day average of 94.0 F. That provided a total of 91 intervals with the average therefore being about 3.6 intervals, meaning that a nine- to ten-day span of three or four consecutive seven-day intervals was the core of the average heat wave. The more intense ones also had longer durations in the range of 10-15 days mostly, with the 1966 case extended with two separate qualifying peaks. Late July and early to mid August 2002 had two rather separate heat waves but they are grouped together since the study will concentrate on years rather than individual heat waves. Of the 25 heat waves that qualified, one was in the interval 1869-1900, three were 1901-30, six were 1931-60, seven were 1961-90 and eight were 1991-2020. When the list was expanded to 48, this produced totals of 4, 6, 14, 11 and 13. The frequency has levelled off since around 1931. To give some idea of the degree of warming, for the 1869-1900 interval to provide six would require the minimum qualification to drop to 92 F, and for 1901-30 to double its total to six would require that we add these three near misses ... 93.14 in 1917 (late July early Aug), and 92.3 in 1923, 1924. ... Summer of 1930 was hot but only managed a peak weekly average of 91.86. One could postulate that NYC summer heat waves have remained steady state under an assumption of a 3F total increase in urban heat island that reduced to 2F by 1931 and rapidly decreased below 1F after 1940. That seems a bit contrived, 2F with a steady decrease is probably more accurate. So some of this change in frequency appears to be natural variability at work. There are only faint signs of any role of AGW in NYC heat wave daily high temperatures. I will add material in a separate post overnight (hopefully) to show that for overnight lows, a different conclusion can be drawn. Then we'll see how that blends together for daily mean temperatures. Some mention should be made of outliers, heat waves that were far enough from the peak of solar warming that they were at a disadvantage in reaching these criteria. The most prominent early outliers were five day heat waves in late May 1880 (91.6 May 24-28) and late May-early June 1895 (94.6 avg May 30-June 3, 93.17 May 29-June 3). These had high enough temperatures but could not sustain a seven-day average to qualify. Sept 20-23 1895 averaged 94.0, but seven-day averages were in the high 80s. In mid-September 1931 there was a mean of 91.0 for the week of Sept 9-15. The average for Sept 20-26 1895 was 89.3 F. Hot spells of about four days in April 1976 and 2002 are even greater outliers. These both averaged around 92 F for four days and had weekly averages near 86F. A second post will give a comparative account of the top 48 years for high seven day averages of summer minimum temperatures. (NOTE: 2023 and 2024 did not provide any new top 50 entries) Table 2: Top 50 Years based on maximum weekly averages of daily minima Without going into quite as much detail, the rank order of highest seven-day average minimum values at NYC is as follows: (note, only the year and its highest average are shown here, to see when these happened, consult the weekly records later in the thread ... 79.29 in 2013 was recorded July 15 to 21. 1. 2013 __ 79.29 _______t27 1876 __ 75.71 2. 1896 __ 79.14 _______t27 2018 __ 75.71 3. 1988 __ 78.14 _______t29 1972 __ 75.43 4. 2011 __ 77.86 _______t29 2020 __ 75.43 5. 1908 __ 77.71 _______t31 1892 __ 75.29 6. 1999 __ 77.43 ______ t31 1911 __ 75.29 7. 2006 __ 77.29 ______ t31 1917 __ 75.29 t8 1905 __ 77.14 _______ t31 1948 __ 75.29 t8 1906 __ 77.14 _______ t31 1955 __ 75.29 t10 1980 __77.00 _______t31 1961 __ 75.29 t10 2022 __77.00 ______t31 1982 __ 75.29 t12 1993 __76.86 ______t31 2005 __ 75.29 t12 2016 __76.86 ______t39 1884 __ 75.14 t14 1898 __76.71 ______ t39 1944 __ 75.14 t14 1981 __76.71 ______ t39 1973 __ 75.14 16. 1995 __76.57 ______ t42 1890 __ 75.00 t17 1885 __76.43 ______t42 2015 __ 75.00 t17 1952 __76.43 ______t44 1887 __ 74.86 t17 1953 __76.43 ______t44 1983 __ 74.86 t17 2010 __76.43 ______t44 1984 __ 74.86 t21 1977 __76.29 ______47. 1870 __ 74.71 t21 2002 __76.29 _____t48 1901 __ 74.57 t23 1909 __76.14 ______t48 1907 __ 74.57 t23 1979 __76.14 ______t48 1938 __ 74.57 t25 2001 __75.86 ______t48 2025 __ 74.57 t25 2024 __75.86______ 52 2019 __ 74.43 _______________________t53 1895, 1900 __ 74.29 ____________________________________________________ Most of the years with the top average maxima are in this list, but quite a few rather average cases (for daytime max) are sprinkled in with them, indicating that some cloudier or more humid spells were included where average max may have been closer to 90F. The frequency distribution is somewhat skewed towards two intervals, the interval 1896 to 1911, and the recent past. As to the earlier interval, it is possible that site interference was playing a role as the station was moved into Central Park from a more urban setting around 1919-20 (or so I am told). So with that in mind, here's the distribution of these top 52 (as 51st place had two tied) years for average minimum in summer heat. The following chart shows the ranks of the distributed cases: 1869-1900 __ 2, t14, t17, t26, t30, t38, t41, t43, 46, t51, t51 1901-30 _____5, t8, t8, t23, t30, t30, t47, t47 1931-60 ____ t17, t17, t30, t30, t38, t47 1961-90 ____ 3, t11, t14, t21, t23, t28, t30, t30, t38, t43, t43 1991-2020 __ 1, 4, 6, 7, t12, t12, 16, t17, t21, 25, t26, t28, t30, t41, 50 2022 ____ t10 ________________________________ So unlike the average maxima, these warmer summer nights are increasing in frequency and severity (note the depth of high ranked cases as well as the frequency). The average for this statistic is 73.34. In the intervals above, the means are 73.4, 72.7, 72.7, 73.2, and 74.4 which is fairly consistent with urban heat island growth combined with site alterations to reduce direct effects. So this suggests that the warmer summer overnight spells are contrasting with recent cases of cooler summers at other times, such as 1992, 2000, 2003, 2004, 2007, 2009 and 2014. After some rest and reflection I will tackle the question of how overall means for these summer heat waves compare. I think it will be a blend of the two different patterns seen. Some further analysis possible now that I have created a similar list of 48 hottest years for weekly averages (not quite the same as 48 top heat waves, 1988 for example had two in the range, and there are two cases in my list that could be taken as two separate heat waves, but as we are studying the frequency of events, a yearly count seems appropriate). Of the above list of top 51 warm overnight low averages, the following ranks do not match a high max top 48, and from inspection I could say that when a year produces both, they are usually in the same heat wave if not exactly the same seven days. So I have listed the 15 of 48 that do not overlap with the mean maximum peak for that year. 5th 1908 _ 89.00 t8 1905 __ 90.43 t8 1906 __ 88.29 t14 1898 __ 91.43 t23 1909 __ 89.71 t23 1979 __ 89.86 t25 2024 __ 91.43 t27 2018 __ 91.57 t29 2020 __ 90.14 t31 1982 __ 92.00 t39 1884 __ 89.57 t42 1890 __ 88.14 t44 1887 __ 89.29 47 1870 __ 89.71 t48 1907 __ 87.71 t48 1938 __ 90.86 t48 2025 __ 90.71 50 2019 __ 90.57 t51 1895 __ 90.14 (this was in late May early June, the interval with the high min avg was Aug 11-17, where peak max avg was 89.14). t50 1900 __ 91.86* * This was a much higher ranking heat wave for both max and min at Toronto, for NYC the peak interval for this max was Aug 6-12 but the peak average min with that heat wave was 72.86 for Aug 7-13, the t50 value of 74.29 applies to Aug 25 to Aug 31 1900 when the peak average max was 89.43). __________________________________________ These include 1898, 1900, all five of 1905-09, and five recent ones (2018, 2019, 2020, 2024, 2025). The somewhat reduced heat of the daytime components may have been due to either cloudiness holding highs down, or the flow pattern favoring sea breezes that would limit the peak warming on at least some days. The 2025 case falls short in maximum average mostly due to short duration, it did average 97.0 for top three days. This means of course that 15 of the 48 hot daytime contenders did not make the list of warmest minimum averages. Those include 1933, 1936, and 1966. Clear skies during those heat waves probably allowed for just enough cooling at night, and this observation is supported by the lack of daily records set, it wasn't a case where several nights were very oppressive and one or two brought the average down, more that the base level of overnight lows was set in the mid rather than high 70s. Another top heat wave (1944) did qualify here but was well down the list from its daytime rank. _______________________ A recent entry for high mean minima was for Aug 3-9 2022 where the mean maximum 92.14 would have ranked t51st and the mean minimum ranked t10th, but the qualifying mean maximum was for July 19-25 (92.43) ranking 44th, and that had a corresponding mean minimum of 76.14 which would have ranked t23rd. The 2024 entry was much more severe for overnight lows also. The 2025 entry is basically a very hot three day interval augmented by four days of moderate warmth that occurred before the heat set in. With a considerably cooler two days following, it seems unlikely that any further warmth (in the future as of time of posting) will affect the final numbers of this entry but I will check it out.

You and I are "newbies" but we've been here since day one, I think, along with all the other newbies. Perhaps Newbie Weather Forum would be a good name for this new look?

I just finished posting all sorts of data tables in one discussion, and now they are all unaligned and the narrower page presentation has all of them wrapping unexpectedly.

If you are making a list of singularities then the 2003 heat wave in Europe should be added, early August, longer duration than recent ones, large death toll from heat prostration in Paris. In historical terms, heat waves in 1911, 1944, 1948, 1953, 1966 are probably in the same league as more recent and better known cases (better known to younger weather weenies at any rate). Not all climate facts point to runaway warming. Toronto has broken 100F on twelve occasions, only one of them since 1953. The annual max for NYC peaked around the 1930s to 1950s and has only recently begun to approach the highest level it attained (running 30-year averages). I think AGW is real and plays a role, but we don't really understand what natural processes are at work in either an unmodified or modified climate, so a lot of this is speculation and guesswork, which tends to invite in a political spin factor since nature abhors a vacuum. But I think we have to be honest and say that we cannot be sure what interaction there might be between human modification and natural variability. And that can be taken any way you want, saying that does not make one a "denier" just a clarifier. The role of AGW could be less or it could be even greater. My main motivation in producing a raftload of climate studies is to try to find foundations for disentangling these signals. I would readily admit it is difficult work.

Table of forecasts for July 2021 FORECASTER _______________ DCA _ NYC _ BOS __ ORD _ ATL _ IAH ___ DEN _ PHX _ SEA ____ bias (rel to con) RJay _______________________ +3.0 _ +3.0 _ +3.0 __ +2.5 _ +1.0 __ 0.0 ___ +3.0 _ +2.5 _ +2.5 ___ +0.63 hudsonvalley21 ____________ +2.2 _ +1.7 _ +1.9 __ +1.3 _ +0.8 _ +0.2 ___ +1.4 _ +1.3 _ +1.4 ___ --0.29 Roger Smith ________________ +2.0 _ +2.2 _ +3.0 __ +3.3 _ +1.5 _ +1.5 ___ +4.0 _ +4.0 _ +3.5 ___ +1.13 DonSutherland1 ____________ +2.0 _ +1.8 _ +1.5 __ +1.5 _ --0.1 _ --0.2 ___ +0.3 _ +1.5 _ +1.7 ___ --0.53 Scotty Lightning ____________ +2.0 _ +1.5 _ +1.0 __ +1.0 _ +1.5 _ +2.0 ___ +1.0 _ +2.0 _ +1.0 ___ --0.20 Tom ________________________ +1.9 _ +1.9 _ +2.0 __ +2.0 _ +1.1 _ +0.5 ___ +1.8 _ +1.5 _ +1.8 ___ --0.03 ___ Consensus ______________ +1.9 _ +2.0 _ +2.2 __ +1.8 _ +0.9 _ +0.1 ___ +1.9 _ +1.8 _ +2.2 so_whats_happening ________+1.8 _ +2.3 _ +2.7 __ +1.7 _ +1.1 _ +0.6 ___ +3.0 _ +2.5 _ +2.4 ___ +0.37 BKViking ____________________+1.8 _ +2.1 _ +2.1 __ +1.9 _ +0.5 _ --1.8 ___ +2.7 _ +1.1 _ +2.9 ___ --0.17 Deformation Zone ___________+1.5 _ +2.0 _ +2.5 __ +2.0 _ +1.5 _ --1.0 ___ +3.5 _ +2.0 _ +2.5 ___ +0.19 wxallannj ___________________ +1.5 _ +2.0 _ +2.3 __ +1.2 _ +0.3 _ --0.8 ___ +1.5 _ +1.0 _ +2.0 ___ --0.42 wxdude64 __________________ +0.7 _ +2.5 _ +2.5 __ +2.2 _ --0.4 _ --0.5 ___ +1.9 _ +2.2 _ +2.6 ___ --0.12 ___ Normal ___________________ 0.0 __ 0.0 __ 0.0 _____ 0.0 __ 0.0 __ 0.0 ______ 0.0 __ 0.0 __ 0.0 ___ --1.64 RodneyS ____________________--0.3 _ +0.5 _ +0.5 __ +0.9 _ --0.9 _ +0.1 ___ +1.1 _ +0.5 _ +2.0 ___ --1.16 ========================================================================= Warmest and coolest forecasts are color coded. Normal is coolest for NYC, BOS, ORD, DEN, PHX, SEA. The consensus values are medians, average of 6th and 7th ranked forecasts. The bias statistic tells your average departure from consensus. The bias of --1.64 for Normal means that our average forecast is +1.64. ________________________ Welcome to Deformation Zone, enjoy the contest.

Actually words CAN describe this heat wave, I just can't post them here. Just got in from a stroll around town, it's almost as hot again but quite a gusty south wind with radar echoes about 100 miles southwest near Grand Coulee WA, probably heading west of my location later this afternoon. Somewhat apprehensive about living in the middle of unbroken forest in every direction, there's no commercial logging except on a very restricted basis near the border, and the forest extends about 50 miles across the border before it thins out to a chaparral style mix of grasslands, scorched tree stumps and valleys full of cottonwood. There are landscapes like that closer to our Okanagan valley also. For people not that familiar with our geography, if you know the layout of inland WA, the Cascades extend a short distance into BC then a range moves west to join the Coast Ranges which are much higher here than in the Olympic Peninsula. Then you have various river valleys and plateaux between those mountains and the Okanagan valley which is quite wide and contains a long freshwater lake almost a hundred miles long and a few miles wide. Kelowna BC is about halfway up this lake on both sides, mostly east; Vernon is at the north end and there's a secondary chain of lakes ending up in the south end of that city; Penticton is on the south end of the lake. Further south, there are two more smaller lakes and the weather station at Osoyoos. This is semi-desert country with a lot of commercial vineyards and fruit orchards. Kamloops is in a fairly similar setting further north in the Thompson valley. That river drains most of east-central BC and joins the Fraser near Ashcroft (north of Lytton and Lillooet). To the east of Kamloops is Shuswap Lake and Salmon Arm. From there south to the U.S. border is a secondary mountain range, the Monashees with peaks in the 8 to 10 k range, not as high or alpine as the Selkirks or Rockies which are parallel ranges further east. Between the Monashees and the Selkirks, the Columbia River has been dammed near Castlegar to form the Arrow Lakes. the weather station at Nakusp is on the north Arrow Lake and gets slight modification as you'll see from its max and records in the past. Between the Selkirks and another similar range, the Purcells, Kootenay Lake is situated and it's a natural feature of the Kootenay (Kootenai on your side) River. That river rises in southeast BC, flows south into Montana, northwest back into BC from Idaho, and joins the Columbia at Castlegar. All of these regions I have mentioned east of the Okanagan are forested and more temperate than semi-arid but near the U.S. border there are patches of open ranching country that is semi-arid (around Grand Forks and Trail). So when people ask, how can it get so hot that far north, really it's the same landscape as you would see in eastern WA, and our elevations are sometimes a bit lower than analogous locations there. Once it gets superheated over inland Pac NW our climate blends in and merges with that climate. This past situation was a bit unusual in that the heat dome did not just have a leisurely connection to the desert southwest like most of our heat waves (and they top out around 38 C as the records being broken will illustrate). This one was separated by a trough near Boise ID to Salt Lake City UT, so that a bit of a relatively cool pocket formed over parts of e NV and central UT into CO and nw NM, ne AZ. This is a fairly unusual midsummer setup although I have seen variations on it before. One of our trips south in Aug 2014 went from heat and sunshine here into cloud and heavy showers in NV and UT, by the time we got to Bryce Canyon it was only 20 C and wet for a day. Looking into the posting of pictures, the limits here are so small even my cheap camera shots are too big to download and I seem to have lost the programs I used to have available to resize pictures.

This is no doubt the early stages but forest fires are growing in extent at a brisk rate, mostly in the Lytton and Kamloops areas so far. Human caused fires are more prevalent than lightning caused so far. One of these fires has moved into outskirts of Lytton and the town is under an evacuation order (it's a town of about 1,500 people). I never went out after the morning coffee run, but from the reports this is the hottest day here with the nearby station reporting 44 C around 4-5 pm. Going out now to catch the sunset and the inevitable drop below 35 C which is probably going to feel good. Our forecast as you probably know is for just a very slight temperature drop combined with an increasing risk of thunderstorms which in our case will blow in from the hills over northeast WA. It is not tinder dry around here despite a rather dry two month period, the winter was relatively moist and the ground moisture in the forests around here will last a few more weeks but eventually the fire hazard here will rise into the extreme category also.

New highs for the year on June 30th __ 95 _ 97 _ 99 _ 96

Another factor to consider is the lack of contrail cloud this year. In Canada especially we have not returned to pre-COVID levels of airline activity and southern BC has a lot of contrail cloud normally, being under the main jet route from Vancouver to central and eastern Canada. It has been quite noticeable that our skies have been very clear in the past year (when clear weather is available from the synoptics of course). In previous years we would have had 10-20 per cent sky cover from contrail debris in some of these hot, sunny episodes. One factor in this extreme heat is probably that the ground had warmed up considerably before the super heat arrived. We had a week near 35 C across the region in advance of this 42-48 C heat wave. The first two days normally would have been less extreme as the ground warmed up, but it already had done so. I am not so sure about thousand or million year return periods, this was a 599 dm high moving inland, it has happened before but not with quite this force of heating. Part of my doubt about return period is that we don't know how extreme this climate may have been in the past, for example, the Anasazi people had built a widespread agricultural civilization in the desert southwest in the 11th and 12th centuries and they suddenly vanished from the landscape around 1180 to 1200 A.D. -- why? Inter-tribal warfare is possibly the reason, but down there most cultural anthropologists seem to think the reason was extreme drought and heat forcing these people out of the region. Some of their ruined settlements show evidence of fires spreading rapidly. This may unfortunately be something we could expect to see, warmed up by 2-3 deg of AGW perhaps. It has to be said that if the 1936 heat wave repeated this summer or any summer soon, we would hear a lot of comments such as "runaway global warming caused this" but unless there's some reason why 1936 should have been that hot, and 2021 should not, I can't see that as a proven theory, just a hypothesis. Anyone can make a hypothesis.

Part three of the NYC "hot week" study analyzing the top averages on a year by year basis. As with the highs where I reported in more detail, consecutive values for 3-4 days (representing 9-10 days elapsed time) may be quite similar. This list ranks the years by top daily values only. Then it compares the sample of years to those identified as hottest daytime and warmest overnight. In the table below, entry "a" refers to the rank of the same year in average 7d maximum and minimum temps, and entry "b" refers to the day shift (if any) between the seven day intervals involved (for mean and max only). A positive number in "b" means that the mean temp max occurred that number of days later than the avg max, and a negative means that it occurred earlier. Zero means that it was the same seven day interval. Where either statistic was on more than one day, the best fit is used but an asterisk will be added. As an example of how to read the table, 1993 (avg 87.43) has the highest seven day mean and also the third highest ranked average maximum and tied 11th warmest minimum (a). The two intervals were concurrent (with reference to the first part of the study, that interval is identified as July 7-13). If b had been entered as "1" then the reference would be to 8-14 July for the mean temperature. If a year failed to make top 48 in mean max or mean min, that entry would read blank or --- . The first example of that is 1991 (t12) which did not register a top 48 7-day average min and the value of 73.57 was a degree lower than 48th ranked values. Two cases are noted (1980, 1999) where the highest average minimum was in a different heat wave than the highest average max. It probably happens more frequently in average and cooler than average summers. Even when the mean max and the mean daily align, the mean minimum peak may be displaced. This is why 2010 came in with a slightly lower mean than 1980 even though its ranks were both slightly better. The relevant ranked mean minimum was displaced one day later. Rank ____ Avg ____ Year ____ a _______ b ________ Rank ___ Avg _____ Year ____ a ______ b _01 _____ 87.43 ___ 1993 ___ 3, t11 ___ 0 _________ 26 ____ 84.43 ___ 1911 ___25, t29 __0 _02 _____ 87.36 ___ 1977 ___ 1, t20 ___ 0 _________ 27 ____ 84.14 ___ 1917 ___t31, t29__0 _03 _____ 87.14 ___ 1953 ___ 2, t16 ___ 0* ________t28 ____ 84.07 ___ 1885 __ t39, t16 __4 _04 _____ 87.07 ___ 1896 ___t13, 2 ___ 0 _________ t28 ____ 84.07 ___ 1898 __ -----, t13 __0 ^^ _05 _____ 86.86 ___ 2013 ___ 23, 1 ___ 1 __________t30 ____ 84.00 ___ 1892 __ t31, t29__ 1 _06 _____ 86.79 ___ 2011 ___ t7, 4 ___ 0* _________ t30 ____ 84.00 ___ 2016 __ ----, t11 __ 1^^ _07 _____ 86.64 ___ 1988 ___ t11, 3 __ 0 __________ 32 ____ 83.86 ___ 1949 __ t44, -----__ 0 _08 _____ 85.86 ___ 1944 ___ 5, t37___1 __________ t33____ 83.79 ___ 1876 __ t49, t25 __ 1 _09 _____ 85.71 ___ 1955 ___ 6, t29 __ 0 __________ t33 ____83.79 ___ 1961 __ t44, t29 __ 0 _10 _____ 85.57 ___ 2001 ___ t11, 24__0 __________t33 ____ 83.79 ___ 1984 __ t39, t42 __ 0 _11 _____ 85.50 ___ 1980 __ t20, t22^_ 0 __________t36 ____83.64 ___ 1982 __ t53, t29 __ 0 t12 _____ 85.43 ___ 1973 ___ t7, t37 __ 0 __________t36 ____83.64 ___ 2018 __ -----, t29 __ 0 t12 _____ 85.43 ___ 1981 ___24, t13 __ 0 __________ 38 ____ 83.57___ 1940 __ t26, ----- __ 0 t12 _____ 85.43 ___ 1991 ___ 4, ----- ___ 0 __________t39 ____ 83.50___ 1872 __ t31, ----- __ 0 _15 _____ 85.36 ___ 2010 __ t13, t16__ 0 __________ t39 ____83.50___ 2005 __ t44, t29 __ 1 _16 _____ 85.29 ___ 2002 __ t22, t20 __0 __________t41 ____ 83.43___ 1937 __ 28, ----- ___ 0 _17 _____ 85.21^___1999 __ ----- 6 ____ 0 __________t41 ____ 83.43 ___ 1972 __ -----, t27 ___--1 _18 _____ 85.14 ___ 1948 __ t15, t29 _ 0 __________t43 ____ 83.36 ___ 1905 __ -----, t8 ____ --5 t19 _____ 84.93 ___ 1901 ___10, t46 __0 __________t43 ____ 83.36 ___ 1908 __ ------, 5 ____ 0 t19 _____ 84.93 ___ 1983 __ t15, t42__ 0 __________t43 ____ 83.36 ___ 1936 __ t20, ----- ___ 0 t19 _____ 84.93 ___ 1995 __ t29, 15 __ 0 __________ 46 ____ 83.21 ___ 1943 ___ t29, ---- ___ 0 t22 _____ 84.79 ___ 1952 __ t31, t16 _ 0 __________t47 ____ 83.07 ___ 1925 ___ t15, ---- ___ 0 t22 _____ 84.79^___ 1966 __ t7, ----- __ 1 __________t47 ____ 83.07___ 2008 ____t37, ---- ___ 1 _24 _____ 84.71 ___ 2006 __ t49, 7 ___0 __________ 49 ____ 82.86 ___ 1979 ____----, t22 ___--4 _25 _____ 84.50 ___ 1933 __ t15, ---- __0 __________ 50 ____ 82.71 ___ 1906 ____ ----, t8 ____ 0 ___________ (min for 1933 74.0, about 0.5 below 48th) ____^^ 1898 mean max 91.14, all peaks Aug 31 to Sept 6 1898 ______________ (min for 1923 in 31st also 74.0) ______________^^ 2016 was similar, max 91.14, mean peak Aug 11-17 2016 _________________________________________________________________________ * Highest mean for 1953 is same as second of two tied intervals for high max (that ending Sept 3). The value for Sept 2 is marginally lower. * Highest mean for 2011 also same as second of two tied intervals for high max (that ending July 27). ^ For the 1980 entry, the mean min for the heat wave with the average shown (July) was slightly lower than a second heat wave with a lower average max. For the heat wave noted, the mean min was 76.14 which ranks t22nd, but for a second heat wave in August which had a mean of 85.00 (Aug 5-11), the average min was 77.00 (also Aug 5-11) and the peak average max 93.57 (Aug 3-9) so the displacement for this one was 2 days, the ranks of the mean max and mean min were t29, 10. In 2002, the earlier noted portion had a mean of 84.79, slightly lower than the peak heat wave, and the minimum of 75.14 was likewise about a degree lower than the peak heat wave recorded. ^ For the 1999 entry, the highest mean occurred in a separate non-qualifying (for mean max) heat wave 22-23 days before tied peaks for mean max later in the summer. The non-qualifying mean max for the overall mean shown was 93.00. This one combined with the 6th highest average minimum of 77.00. After three weeks of less prolific heat, a second heat wave set the qualifying 95.00 peak (t15th warmest) on two consecutive days (for seven day averages) but with that heat wave the corresponding mean min was 74.71 which ranks t45 with otherwise untied 1870 (about t47 for separate heat waves). So 1999 set the 15th warmest mean max and 6th warmest mean min, although three weeks apart, and had two ranking heat waves for mean temperature if that were the criteria for counting. ^ For the 1966 entry, the highest min was slightly lower than 48th. A later portion of the extended heat wave as noted had a slightly lower value of mean minimum attached also. The mean for the second interval was 83.57 which was 1.22 below the main peak ten days earlier. This is not considered to be a separate heat wave but an extended portion of the qualifying case. (notes about secondary peaks, in 1955 the earlier July sub-peak had a mean of 85.29 (zero days displacement relative to mean max) -- this would rank as 23rd highest heat wave mean temp and would combine equivalent t10 mean daytime max with equivalent t37 mean min (almost equal to the later main entry heat wave), in 1953 the July heat wave (listed as 2b for mean max) had a mean of 83.50 displaced one day later than the mean max peak, and a mean minimum of 73.43 which would rank outside the top 48 by about one degree, while in 1988 the earlier July sub-peak had a mean of 82.79 five days after the mean max peak showing the longevity of that heat wave). This one would rank t27 for heat wave mean max, and its mean minimum finished well outside the top 48. The heat waves of 1905 to 1908 and also 1979 generally levelled off near 88-90F and had warmer ranked overnight lows in the 75-77 range, for unusually small diurnal ranges. This may indicate frequent sea breeze modification, or cloudiness. _________________________________________ ANALYSIS of the frequency of hot average daily temp 7d intervals This shows the ranks of each member of the five intervals in the study ... ranks of mean max and mean min in brackets. Almost all the heat waves produced overlapping intervals of peak mean max and mean min, sometimes there was a one-day lag and in a few cases longer displacements. The greater the displacement, the more the apparent error in the rank attained by the year's highest mean daily (since it has not been derived precisely from these ranked components). Two cases required that two heat waves during the year be re-ranked from the annual rankings as the high min and high max were in two different heat waves. In both cases the differentials are rather small and explained in the text above. 1980 is the highest ranked heat wave to have its mean minimum finish second to another heat wave during the summer (that one while cooler for max temps ranked 10th overall for mean min, its max component ranked the same as 29th annually). n __ interval __ cases 6 __ 1869-1900 _ 1896 4th (t13, 2), 1885 t28 (t39, t16 ), 1898 t28 (---, t13), 1892 t30 (t31, t29), ____ 1876 t33 (t49, t25), 1872 t39 (t31, ---) 7 __ 1901-1930 _ 1901 t19 (10, t46), 1911 26th (25, t29), 1917 27th (t31, t29), 1905, t43 (---, t8), _____ 1908, t43 (---, 5), 1925, t47 (t15, ---), 1906 50th (---, t8). 11 _ 1931-1960 _ 1953 3rd (2, t16), 1944 8th (5, t37), 1955 9th (6, t29), 1948 18th (t15, t29), 1952 t22 (t31, t16), _____1933 25th (t15, ---), 1949 32nd (t44, ---), 1940 38th (t26, ---), 1937 t41 (---, t27), 1936 t43 (t20, ---), 1943 46th (t29, ---). 12 _ 1961-1990 _ 1977 2nd (1, t20), 1988 7th (t11, 3), 1980 11th (t20, t22), 1973 t12 (t7, t37), 1981 t12 (24, t13), 1983 t19 (t15, t42), _____1966 t22 (t7, ---), 1961 t33 (t44, t29), 1984 t33 (t39, t42), 1982 t36 (t53, t29), 1972 t41 (---, t27), 1979 49th (---, t22). 15 _ 1991-2020 _ 1993 1st (3, t11), 2013 5th (23, 1), 2011 6th (t7, 4), 2001 10th (t11, 24), 1991 t12 (4, ---), _____ 2010 15th (t13, t16), 2002 16th (t22, t20), 1999 17th (----, 6), 1995 t19 (t29, 15), 2006 24th (t49, 7), ______2016 t30 (---, t11), 2018 t36 (--- t29), 2005 t39 (t44, t29), 2008 t47 (t37, ----). ______________________________________________________________ The pace of these top 50 heat waves (average temp) has been gradually increasing but of the 15 in the most recent 30 years, about one-third are included mostly for their unusually warm nights. This was also the case in the earliest interval. The daytime highs dominated most around 1931-60.

There was some talk earlier about breaking records by large margins -- this is exactly what happened in Toronto during the 1936 heat wave. At that point, Toronto (downtown) had been running a weather station for 96 years. These were the records before and after the 1936 heat wave. I have added the hottest values since 1936 as in some cases those are now in second place. Date ____ previous record ____ 1936 _____ hottest since 1936 July 8 ___ 93 1876 ___________ 105 ______ 98 1988 July 9 ___ 94 1911 ___________ 105 ______ 96 1974 July 10 __ 91 1912 ___________ 105 ______ 98 1988 July 11 __ 95 1846 ____________ 96 ______ 93 1987, 2005 July 12 __ 92 1887, 1908 ______t 92 _____ 94 2005 July 13 __ 95 1845, 1921 ______100 _____ 94 2005 ... also Dec 3 1982 at Toronto hit 68 F, the previous record was 58F in 1973, since 1982 the warmest on the date is also 58 (1998). _________________________________________________________ Here are some examples of records blown away at NYC (period of record 1869-2021) by large margins ... Apr 7, 1929 ___ 89 (previous record 75 1908) _ since broken once, 92 2010 May 19, 1962 __ 99 (previous record 88 1903) _ warmest since was 91 2017 Nov 1, 1950 ___ 84 (previous record 73 1927,29) _ warmest since was 81 1974 Dec 24, 2015 __ 72 (previous record 63 1990, 96) ___ these are comparable landmark record breakers that came to mind, in Britain I think 31 Oct 2014 broke previous marks by a similar margin.

Some action in this contest today ... The new maxima for the year are 94 _ 94 _ 97 _ 95 and 108 for Roger Smith (it is scorching hot outside my place these past few days, and I'm up at about the elevation of the highest peaks of WV).

The humidity levels are tolerable, so it's just a case of waiting it out. A cold bath helps too.

I would explain the Lytton increase as the marine front forcing all the hot air out of the central Fraser valley downstream, and through the canyon. The marine front has pushed past Abbotsford now but it has been around 105-110 F in that lower elevation for two days, so forcing that air upslope is likely to compress it, then Lytton is at a slightly lower elevation than much of the canyon so it gains some heat coming out of there. May also be all the journalists in town revving their engines to see if the locals will come out of their a/c homes for interviews. "What's it like to live in Canada's hottest town?" Sort of like asking what's it like to be Liechtenstein's greatest footballer.

The other thing about PDT is the weather station is now at an airport and in 1898 could have been at a hotter location in the town or lower down in elevation. However we may as well get some 120 readings in this heat wave to end the debate. With those Prineville readings once again I would raise the question of wildfire heat release, that location is near the center of Oregon's logging industry (it is now the center of the tire industry with a major company's shipping facilities located there, important enough to get a new state highway built to connect existing highways). We have been told by media and experts that the wildfire situation is getting worse, which is probably true when comparing modern conditions to the 1951-80 reference period but if you go back further then we're talking about frequent uncontrolled blazes, historical accounts from southern interior of BC talk about widespread forest fires and smoke in the 1920s for example (and that was not a particularly warm decade, but they just weren't organized to fight forest fires back in those days, once they started, they burned through everything in their path until the fall rains put them out).

Marine layers spreading into Puget Sound, Fraser valley and Columbia valley (Cascades being the limit so far), keeping temperatures more moderate in coastal locations so far today. Roasting heat continues further inland though. Looks like a worse situation may develop, we can take the heat for a few days but if dry thunderstorms erupt along the weak frontal boundaries depicted for Thursday to Sunday, then forest fires are sure to follow. They may not need to be entirely dry, rainfalls of .10" or so have very little effect with numerous lightning strikes over forested areas, and that is typical of our climate. The July 1941 heat wave ended with similar sporadic thunderstorms and limited amounts of rain.

Here's a thought about 1898, they made no organized efforts to fight wild fires back then, and Pendleton is just to the west of a complex of hills and mountains with forests and open woodland areas that even today have high rates of wild fire starts (they probably don't spread into huge conflagrations as they used to do). So I wonder if it's possible that such an event in 1898 created a firestorm and outflow winds that might have advected at least 5 F additional heat. Just in more general terms, what would be the NWS policy on a temperature that was evidently boosted by a very close encounter with a wildfire in the vicinity? Sooner or later it would happen, if it hasn't already happened. Temperatures within firestorms are known to be several hundred degrees and if you have 30-50 mph winds flowing out of these fires, it stands to reason that some increase would be seen miles away from the burn zone. (the smoke certainly travels a lot further|)

Were some of those vintage temperatures not properly screened? I have been working with various long-term data sets and have seen many discussions of how to compare them. Part of the problem is we can't always be sure how much modification was created (and should therefore be eliminated). Death Valley's 134 record was in 1913, I thought. So we're saying that may have only been 128 to 131? Seems logical because at better situated long-term locations, highest values from the 1911-20 decade, while impressive, run 2-3 lower than the 1930s at many locations. For example, Toronto had 103F in July 1911 and 100F in July 1916. It had 105F in July 1936. As far as I know these readings were taken from the same thermometers at the same location (in downtown Toronto). What's interesting is that Toronto has hit 100F about a dozen times, only one of those is since 1953 (2011). It is warmer nights making the bulk of the recent warming (this does not apply to winter as much, more daytime records have fallen then, especially late Nov-early Dec and late Feb- early March).

+2.0 _ +2.2 _ +3.0 _ +3.3 _ +1.5 _ +1.5 _ +4.0 _ +4.0 _ +3.5

Well now 108 has replaced the previous all-time record set the previous day. I am super depressed because I am under the same heat dome with the same temperature here. (Canadian all-time record fell yesterday, now 47.9 C which is 118 F, mind you it's a dry heat, dew points in the 50s).

In terms of the social or political response to the climate change aspect, you're going to find a certain amount of mission fatigue there, in BC we have been paying large carbon taxes for ten years, our electricity grid here is almost all hydro-electric (no coal-fired plants involved) and there has been a considerable move to electric and hybrid vehicles. Urban bus fleets have been converted to natural gas. A common theme in everyday discussion about this is that we have done our share but other signatories to international conventions either have not or they are exempt while they develop. I could also say that about half the population would probably agree that the heat wave is "largely" caused by AGW, while the other half probably take the position that this is a natural event maybe warmed up by 1-2 degrees. If the latter, then what can be done? This would be every bit as bad at 116 as at 118, so people take the position that maybe adaptation is more realistic than prevention if there is a natural component to this that we cannot influence. I have been trying to find ways of answering this rather thorny question, by analyzing a ton of climate data for various locations, and have to admit that there is no easy answer, climate has always had this tendency to push limits and extremes. The 1936 heat wave must rank as a greater "singularity" than this event, which introduces the question of why that happened when it did, and whether it might repeat. A sort of weak effort to repeat it in 1995 turned out more humid which seemed to cap the extremity of temperatures although I recall humidex values in Iowa and Illinois which were probably equally oppressive, I mean would you rather have 110/75 or 102/89 temp dew point? This dry heat is considerably more tolerable from a physiological point of view, even with this degree of heat here now, I used to feel more uncomfortable with average summer heat in Ontario where the dew points were a lot higher. Many people in the Pac NW and BC travel south at various times, including the summer in some cases, so these temperatures are probably familiar to most of us. I was in Las Vegas in August 2011 (flew in to start a holiday in less brutally hot higher parts of Utah) and it was close to their all-time high, 116 F at both ends of our trip. So with it being 108 F here yesterday, I had that reference point and what I recall was that it cooled down even less at night in Las Vegas (actually in Mesquite to be precise about the overnight) with a "low" of about 90 F. Personally I think people will probably go along with whatever responses governments choose to make but obviously they can't just shut down entire economies on the spot, the problems that would create would be thousands of times worse than these occasional climate episodes. And we could predict what would happen to political parties that tried that approach, especially in some environment where China and India were given a pass and allowed to continue with their high polluting ways. I would note also that while all this talk goes on, we have missed a chance to go into major desalination projects that would at least solve growing water problems in the western U.S., and I don't understand (from a distance) how high speed trains that cost billions of dollars form a better use of public money than major desalination projects might do. The same could be said about a lot of things that money is wasted on in this world. Expecting an even hotter day here today as the heat dome has shifted towards north Idaho so we're in that zone with a slight southerly flow aloft now.

Just looking at the 00z 500 mb chart, it shows 597 dm high right over my location. I for one welcome our alien visitors. There's a slug of 594-97 thickness shown over south central OR and the 588 dm thickness is basically overlapping the 594 dm height oval (except in the southern portion where it continues south into CA). The GEG sounding has a -4C temp at 500 mb. The 850 mb chart has readings in the mid 30s but you have to keep in mind most of southern BC except for valley floors is land up to and even above the 850 mb elevation, where I live is probably around 900 mb. So my 42 C air temp would be a 900 mb temp I suppose. The nearby ski hill is probably within shouting distance of 850 mb and up there it is probably around 35-37 C. Took some pictures during the heat to illustrate this thread (a picture is worth a hundred words in my case).

Looks like that all-time Canadian record lasted one day, it's edging up to 47 C at Lytton BC now. Probably the most remarkable temperature on the list is 40 C in downtown Victoria BC. YVR maintains a sea breeze and is stalled at 31 C, however, as I said that reflects almost nothing about what two million people in greater Vancouver have outside their homes, the range for 90% of the urban area is probably 36 to 41 C at present. A few lucky seafront areas are in the 20s. Another traditional hotspot, Osoyoos, is up to near 43C and Warfield near my location is 42.2 C. Have to say I am acclimatizing to this, if you take a very cold bath about twice a day and don't exert yourself, it feels comfortable enough inside, we don't have a thermostat because there's no heating system to control here but it feels like it's about 32 C (90F) inside. Somebody called to ask if I was okay being an old person, so I said sure thing, this is nothing compared to 1936 in North Dakota, had to take off the t-shirt for that one.

I was not aware of any predictions of 112 for SEA unless they were humidex predictions (which verified near that level). I watch local SEA and GEG t.v. news and weather segments and the general range of predictions was accurate in all regions (same in BC). We knew this was coming a week ago and it has been on the news cycle in terms of get ready for about a week. All of these coastal urban areas have very large variations from one part of town to another, so the airport high is just part of a greater complexity. YVR is more marine-modified than most of the urban area it represents and a better idea of conditions for most of the two million residents of greater Vancouver can be gained from the Pitt Meadows station which is inland (Abbotsford even more so). For Seattle and Tacoma, SEA is also somewhat more exposed to sea breezes than large parts of those two cities but at the same time a few neighborhoods of Seattle are probably more exposed than SEA to sea breezes. Here again, in some heat waves you'll get a better representative temperature from McChord Air Force Base which is situated between the two cities and inland several miles. The bottom line is, it is dangerously hot in a coastal region that does not get a lot of severe heat waves even in peak season. Our climate is a bit different from the east coast, we don't just glide into summer through June, quite often there's a long delay of full summer heat and drought (which is normal there for about 6-8 weeks) until the second half of July. Even in the hotter interior regions, June is usually quite temperate and the main heat arrives in mid to late July and persists through most of August. That's the main story here, a full on midsummer heat wave in June is considered odd here, I wouldn't imagine it would seem that odd in NYC or DC (although mean temps are still rising in late June and so are daily records, the differential is larger out here at least by the coast).