TheClimateChanger

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.

Looking at NowData, there are only two instances of a high greater than 90 after August 9 - August 28, 1973 & September 3, 2011. Bradford registered it’s earliest 90+ reading on record just last year, when it reached 90 on June 16, 2022. The prior record was July 2, 1966.

May see some monthly all-time record highs in some of the higher elevations with the upcoming heat wave. Bradford could possibly see it’s latest 90 degree day on record, and DuBois could approach the monthly record high of 91.

Will be interesting to see whether IAD can eclipse the monthly record of 99F, and set a new latest date for a maximum of 100F or better. The current record is August 27, 1987, when it reached exactly 100F.

Although outside this subforum, worth noting Denver reached 99 today. I checked on NowData, and that was a daily record and equals the third warmest reading on record in the month of September. The only warmer readings were 100 on September 2, 2019, and 101 on September 5, 2020. It also reached 99 on September 7 & 8, 2022, and September 10, 2021. Prior to 2019, it had never reached 98 in Denver in the month of September. With today’s high of 99, it has now reached 98 or better on nine occasions in the past 5 years. In the context of the past five years, a pretty typical early September heat wave in Denver. But it would have been a new monthly record high prior to 2019. Records for Denver date to 1872.

How closely do the PRISM numbers agree with the officially tallies from NOAA? A mean of 72.98F would be 15th warmest overall, between 2007 & 1933. I would have thought this would be a Top 10 hottest summer with the record-breaking heat in the south and parts of the west. Note that the PRISM anomaly is based off 1991-2020 climatology, whereas the NOAA anomalies are based off the cooler 20th century mean [1901-2000]. Also worth noting that while this may be the 15th warmest summer overall, it is warmer nationally than all but three summers prior to 2000 (those three being the notorious drought years of 1934, 1936 & 1988).

The NWS point-click forecast centered on KMSP, shows a high of 96 on Saturday, 100 on Sunday, and 99 on Labor Day (see below). Saturday's forecast value is one shy of the daily record, and the other two would be new daily records. More significantly, this would be the second latest 100+ reading on record for the Minneapolis-St. Paul area. The latest 100+ reading is September 10, 1931, when the mercury is said to have climbed to an incredible 104F. That is the only 100+ reading on record in the month of September in the Minneapolis-St. Paul area dating back to 1872. The current second latest 100+ reading is August 17, 1947, when it reached exactly 100F, so that September 10, 1931 is really an aberration. Obviously, can't break the September 10, 1931 record, but there is a decent chance of the second latest 100+ reading on record, and potentially the first time two days of 100+ were recorded in the month of September if Labor Day is just slightly warmer than presently forecast. For the record, there is only one occasion when the month of August has had more than one 100+ reading in the Minneapolis-St. Paul threaded record - 1947, when it reached that figure 4 times. And there are only two dates in the entire threaded history where it's reached 100 or better after August 15 - 8/17/1947 & 9/10/1931.

Old Farmer's Almanac says an old-fashioned winter wonderland is on tap for this winter. I'm not so sure I believe this, especially with a potential Super El Nino. They even claim it will snow for the Steelers home game on December 23rd. I think when you start making specific predictions like that, you're no longer practicing any semblance of meteorology, or science, but something more akin to astrology or pseudoscience.

Sorry, it's difficult to be optimistic. Even in a relatively cooler summer, it's still exceedingly difficult to come anywhere near cold records. I think the low at PIT in the current cool snap was 58 this morning, which is only a couple degrees below normal. As an aside, excluding today, PIT has averaged 55.3F over the first eight months of the year. The last 8 years have averaged 54.7 for Jan-Aug, and the last 14 years have averaged 54.3 for Jan-Aug. By comparison, the mean at Clarksburg, West Virginia for Jan-Aug from 1948 to 1980 was 53.9F. We are now warmer than the typical climate in Clarksburg, West Virginia for the mid to latter part of the 20th century. This year has also been warmer than about 1 in every 4 years over that same stretch at Charleston, West Virgina, and the mean at PIT for the past 8 years is warmer than roughly 1 in 6 years at Charleston, West Virginia for the period 1948-1980. In other words, the last 10-15 years at PIT are now warmer than a typical mid/late 20th century climate in northern West Virginia, and approaching the 20-25th percentile of similar elevations in southern West Virginia. Hard to be an optimist. And like I said, I'm not even looking at 1800s or early 1900s, I'm just looking at temperature records only a little more than 40-70 years ago. Probably in the lifetime of some posters here. And it might be easy to blame the heat island, but I would point out Clarksburg has averaged 57.8F so far this year (2.5F warmer than PIT) and Charleston has averaged 58.8F (3.5F warmer than PIT). So if it's that, then there must be some urban warming to blame in West Virginia as well.

Ok, well, it looks like eastern Pennsylvania did a bit better in terms of cold. The 44F at Mount Pocono was only the 33rd warmest minimum for the month of August (since 1902). In western Pennsylvania, whenever there is a cold snap these days, it's accompanied by thick stratocumulus from the Great Lakes preventing radiational cooling from occurring. But, on the same token, Mount Pocono has not been below 40F in the month of August since 1992. From 1902-1992 - a total of 92 years, but for which only data exists for only 86 years - there were 46 years in which the temperature dropped below 40F in the month of August. In other words, a temperature that used to be observed more frequently than every other year has not occurred in over three decades.

As I noted here, it was at or below freezing throughout western Pennsylvania outside of the heat island areas in August 1982. It was even 38F in suburban Washington, D.C. at Dulles International Airport. What was the low temperature in Cashtown in August 1982? Are you saying the ASOS temperatures are incorrect or unreliable? And, if so, why would they just start being wrong in recent years?