TheClimateChanger

Another 90 today officially. Only question is how much, if any, above that we get. 2nd in a row, but only 4th of the calendar year.

4th warmest first eight months at IPT [tied with 1991] 3rd warmest at PHL [tied with 2022 & 2002] 4th warmest first eight months at MPO And 1st place at my favorite locations - DuBois & Bradford *4 of top 9 in last 4 years at DuBois; 4 of top 7 in last 4 years at Bradford* Incredible stuff, can only begin to imagine what 2024 is going to look like if we get a super Nino.

Through August, Harrisburg is just a tenth of a degree below 2012 for hottest first eight months of the year and tied for second place with 2020. At Harrisburg, the 1951-1980 average for January through August was 54.8F, and the 1961-1990 average for January through August was 54.6F. In the last 14 years (2010-2023, inclusive), the January through August timeframe has averaged 56.9F. The mean of the last 14 years would rank as the 18th warmest year in the 135 year threaded record, if it was a single year's data.

BWI also doing quite well in the rankings.

Washington Dulles (IAD) has set three hourly heat records for the month of September, and tied an additional six hourly records during the current hot stretch.

Here's the histogram of hourly heat indices above 100F in the month of September, showing the single observation from 1952, which occurred during the 4 pm hour. Does not appear this will change this week, as heat indices should peak no higher than about 95F.

Some statistics for September heat, dating back to 1945. Here are the highest hourly temperatures at Pittsburgh International Airport (any data prior to 1952 would be from Allegheny County Airport). Unfortunately, there is some bad data. The 4 hourly observations from 1989 are incorrect. Looks like somehow the time of those observations got crossed. The high was 87 that day, and it was in the upper 60s during the morning. Here are the highest heat indices observed in the month of September. There is only one time in which the heat index has exceeded 100F in the month of September. On September 11, 1952, at 4 pm, the heat index reached 101F. That is the only hourly observation of a heat index in excess of 100F at PIT in the month of September. See note above about the 1989 values, which again are incorrect.

Wow! Looks like it's only 0.01C below the anomaly for February 2016, for second highest of any month. Given the global temperature peaks during northern hemisphere summer, I would assume it's safe to say either July or August of this year was easily the highest absolute temperature of any month in the satellite record. Also worth noting that El Nino temperature peaks invariably occur in the first half of the year following the inception of the El Nino event, so we almost certainly will see these values continue to go up. Dr. Spencer may need to raise the y-axis if this keeps up.

Your side of the state has more 90+ days than PIT has had in three years. Tacked on number three for the year today. There have been only 12 90+ degree days over the past three years at PIT (5 in 2021, 4 in 2022, and 3 in 2023).

The high of 97 at York Airport (THV) was the highest reading at that location since July 7, 2012, when it reached 99. The high of 98 at Lancaster Airport (LNS) matches the highest reading at that location since July 7, 2012, when it reached 101. It also reached 98 on June 30, 2021.

Yup, reached 91, which matches July 28th for the highest of the year. Only the third 90+ of the year, although the current forecast has 91 for tomorrow & 90 on Wednesday for the airport. After that, it looks like we may be done for 90s until next year, although you can’t rule out an isolated 90+ even into late September.

The record is 93 for September 4. 102F is the record for September 4th.

Some insight on the pre-1895 cold years. 1836 was a volcanic summer following the eruption of Nicaragua's Cosiguina volcano. According to an analysis by Berkely Earth, global land temperatures plummeted around 0.75C. And this was already a cooler period towards the end of the Little Ice Age. See here: Cosigüina - Wikipedia I have a mean temperature of 61.9F at Fort Dearborn in Chicago, 60.5F at Fort Dearbornville in Dearborn, Michigan, 63.0F at Rochester, New York, and 68.5F at Allegheny Arsenal in Pittsburgh [elevation: ~700 feet]. These are averages of 7 am, 2 pm and 9 pm measurements, and keep in mind, these times predate daylight saving time and standardized time zones. Local solar time was still in use, so there's a small warm bias (more predominant early in the summer) since the 7 am reading would have been well after sunrise. The 9 pm reading was included to partially ameliorate this effect, but there is still a significant residual bias. August 1866 was also very chilly. Here are the daily maximum and minimum readings for Lansing, Michigan and downtown Toronto, Ontario, from that month. At Toronto, the mean temperature was 61.2F, with an average maximum temperature of 69.7F and an average minimum temperature of 52.7F. The maximum temperature for the month was 77F, recorded on August 1, 6 & 7. The coldest reading was 42F on the 24th. At Lansing, the mean temperature was 59.9F, with an average maximum temperature of 71.6F and an average minimum temperature of 48.3F. The maximum temperature for the month was 80F on the 14th, and the coldest was 34F on the 24th. August 1866 is the coldest August on record for both Lansing and downtown Toronto. I have no data for either location in 1836. Not too concerned about urban warming impacts, because you have to look to small towns in far northern lower Michigan to find similar mean temperatures for August among relatively more modern records. The coldest August on record for Houghton Lake (population: 5,294; Roscommon County population: 23,459) is 59.7F, in 1919. The coldest August on record for Alpena (population: 10,197; Alpena County population: 28,907) is 60.1F, set in 1934.

@Brian D Here is what I have for August in the lower Lakes region. August 2023 was near the long-term mean, but a bit below trend. In general, warmer anomalies were noted in the western parts of the region, with cooler anomalies in the east last month. Quick sanity check. NOAA's NCEI for the whole Great Lakes region also has August 1947 as warmest, with 1955 & 1995 tied for 2nd, and 1959 & 2016 tied for 4th. They have 2021 in 7th place, and I have 1959 in 6th place. They have 1900 in 6th place, whereas I have it in 7th place in my dataset. So the top seven are identical, just in different orders. I may have a residual urban warming bias, resulting in recent years placing slightly higher. But again I'm focusing on only a subset of this basin, so it's not an apples to apples comparison. They have 1927 as coldest, followed by 1915. I have 1927 as the coldest in the post 1895-era, and 3rd coldest overall. 1915 is the 2nd coldest in my dataset in the post-1895 era, and 6th coldest overall. Overall, the rankings match pretty well with NCEI's rankings for the Great Lakes basin in the post-1895 era.

HRRR suggesting up to 100F in parts of the western UP, south of the Keweenaw Peninsula. Here is the sounding for 46.81N, 88.68W for 21z, showing a temperature of 100F and dewpoint of 48F.

Here is the regional weather summary for northern Wisconsin, showing several stations in the low 100s today.

Stevens Point, Wisconsin reached 102, with a dewpoint falling into the 30s: National Weather Service : Observed Weather for past 3 Days : Stevens Point Municipal Airport Not a first order site, however, so there could be data problems. Very limited period of record and a lot of missing data, but looking back to 2009, the highest I could find there prior to today was 97F on June 6, 2011, July 17, 2011 & July 20, 2011. Just to the north, at a first order station with a long POR, Wausau reached 99. This matches the September monthly record set on September 10, 1931. It also matches the highest reading ever recorded in the month of August - 99 was observed on August 2, 1964; August 16, 1988; August 21, 1955; and August 24, 1948. Since 1936, only one date has been warmer than today at Wausau - July 13, 1995, when it reached 102F. That is also the only 100+ reading since records moved to the airport in 1942 in the threaded station history. There were 14 100+ readings prior to the station move - half of which occurred in 1936, and all but one of which occurred between 1931 and 1936.

The dreaded 89 today, but 90 looks like a good bet tomorrow through Wednesday. Dulles Airport, near Washington, D.C. reached 99F today.

Additionally, Dulles Airport reached 99F today, matching the all-time September monthly record set on September 2, 1980, September 10, 1983 & September 11, 1983. There is a good shot at the temperature climbing into the triple digits for the first time on record in the month of September in the coming days.

Dulles Airport reached 99F, matching its monthly record high set on September 2, 1980, and September 10 & 11, 1983.

Some observations I have shared on the Lakes/OV subforum regarding the ongoing heat wave. I figured I'd share here for a larger audience with the climate buffs. More to come in the coming days, no doubt. I found the data from Denver quite shocking, with no readings above 97 degrees prior to 2019 in the month of September, and now 9 of them since then. Also, very impressive heat in northern Minnesota today, with Duluth easily eclipsing the September monthly record. There has not been a hotter day than today at Brainerd since July 1936, and this is now the third year in a row with a 100F or better reading there, which is unprecedented in the historical record. September 1 September 2 September 3

Brainerd reached 102F today, one shy of the September monthly record set on September 10, 1931. It was the hottest day since July 15, 2006, and would have matched the August monthly record which was set on August 4, 1947. Only four days in recorded history were hotter than today at Brainerd - the aforementioned 103F reading from September 10, 1931; July 10, 1936 (106F); July 11, 1936 (103F) and July 12, 1936 (103F). Which is to say it has not been hotter than today at Brainerd since July 12, 1936, during the most impressive heat wave of the Dust Bowl. At more than 87 years ago, I would venture to guess few living Brainerdians have experienced a day hotter than today, and fewer still would have been old enough to recall it. It has now reached 100F or better three years in a row - it was 100F on June 4, 2021 (earliest on record) and 100F on June 20, 2022. Both of those dates tied the June monthly record of 100F set on June 19, 1988. It does not appear there had ever been two years in a row with a 100+ reading prior to the current stretch of 3 years. This in a place better known for snow and the Coen brothers cult classic, Fargo, which, of course, featured plenty of snow and a gory wood chipper.

Okay, so Duluth might be the most impressive record yet. Hit 97 today, breaking the previous September all-time monthly record by 2 degrees set on September 7, 1976. It shattered the daily record by 8 degrees. Prior to today, the latest 97 or higher reading at Duluth was on August 1, 1930, when it also reached 97 degrees. Which is to say, yes, this would have tied the August monthly record as well. The low of 71, should it hold, would be just one shy of the highest on record for the month. And the mean of 84F easily bearing the prior record of 82F. Both of those records are from September 11, 1931, I believe. I do say “should it hold” since I am aware Duluth is prone to lake breezes which can result in rapid temperature swings. I don’t believe that’s the case today, but I didn’t investigate.

A couple other observations. The high of 101 in Sioux Falls, South Dakota was the first 100+ reading in the month of September at that location since 1976, and only the seventh year to achieve that figure. The high is again forecast to be around 101F today, and if it achieves that, this would be the first year with more than one 100+ readings in over 100 years (1922 was the last year with that distinction). The high of 102F at Sioux City, IA was the first 100+ reading in the month of September at that location since 2000, and was also just one shy of the monthly all-time record of 103F. This was also only the eighth year that has reached 100 in September. Should it reach 100 today, it would be the first year with more than one 100 degree reading in September since 1939, and third overall (1895, being the other).

Impressive heat in parts of South Dakota today. Winner reached 107F, one shy of the all-time record for the month of September set on September 9, 1931, and the second warmest reading on record for the month. The low of 76F was also the second warmest of record, behind 78F on September 7, 1945. The daily mean of 91.5F was easily the hottest of record in the month of September. The old record was 89.0F, set on September 2, 1983 & September 8, 1931. In fact, the 91.5F daily mean is the easily the latest in the calendar year that value was attained. A daily mean of 91.5F was reached on August 16, 1988, which is the latest date other than today on which a daily mean equal to or greater than today’s value was attained at Winner, SD.