TheClimateChanger

Definitely living up to its billing as the swamp. I was shocked with widespread 100-110F heat indices, that there is not even a heat advisory. I think most places in the US would melt in those conditions. Yikes.

Looks like those were mostly urban heat island driven heat waves. Much cooler in the 'burbs and sticks back then.

With that said, still a far cry from the olden days of the 2010s, when DCA would far outpace all other sites in the CWA not named "Maryland Science Center." Looks like they got most of that so-called UHI in check at National Airport. At the height of its urban heating days, in 2015, it was 1.5F warmer than any other site. Even beating DMH by 1.8F. With the 2015 sensor in place, would probably be making a run for record warmest. 2025 2010 2015

Surprised to see DCA is only running +0.5F for the month. Looks to be the lowest of all sites (including reporting cooperative observations) in the IWX CWA, with the majority of stations running between +1.5F and 3.5F. There were a couple stations with an anomaly close to that of DCA, and a few warm outliers (> +4F), but DCA looks to have the lowest anomaly of all sites. It is worth noting that the "normal" is 0.5F above the 1991-2020 mean, so if not for that added warming from NOAA, it would be +1.0F for the month and more in line with surrounding sites. Most of the co-op "normals" are just based on simple averages, I do believe. As an aside, I always cringe when people object to calling it a "normal" and instead call it "average" when it's NOT an average. The justification being there's no such thing as normal in climate, ignoring that the term has a specific meaning in this context, and calling it an average is just plain incorrect. I have seen some stations where the "normal" is as much as 1.5F above the 1991-2020 mean.

Looking at the numbers, mean summertime high temperatures for the most recent 15 years (2010-2024) are about 1.5-2.5F warmer in most places in the eastern US, compared to the preceding 15 years (1995-2009). Have to wonder how much of that is attributable to a climate signal and how much of that is attributable to the 2010 amendments to the Clean Air Act.

This is a good point. I remember in the 1990s, we had "triple H" weather - hazy, hot and humid, as though haze were a byproduct of hot and humid weather rather than a noxious soup of industrial chemicals. It was common for airport visibility to be 5-7 miles in heat domes, sometimes even 3-5 miles. Compared to today's atmosphere, you don't see such things. In fact, it used to be northwest flow would bring in clean, crisp, unpolluted air from the hinterlands. Now it brings in toxic wildfire smoke and particulates. So more often than not, we wind up with hazy, cool and dry weather, instead of the opposite.

Some very impressive anomalies out there, with several sites reporting temperatures as much as 5-7F above the 1991-2020 mean. Very impressive deviations relative to normal for a summertime month. The New York City metro area has actually been relatively cool compared to many locales. Widening out a bit (not depicted), the west also has seen similar departures relative to normal, despite a recent cold snap that brought snow to the higher elevations. Looks like this could be one of the warmest Junes on record for the CONUS as a whole. Although I highly doubt we will unseat 2021 for the record warmest, which had some truly insane +6-8F anomalies across much of the intermountain west.

I mean this is just an anthropocene signal, no? Looks like something a climate model would spit out with a cooling hole in July over the heavy agricultural areas due to the unnatural densities of corn and soybeans (and the resulting unnatural levels of evapotranspiration) and irrigation effects, enhanced warming over the arid west with rapid winter warming east of the Rockies.

Looks like it. Should finish around 73.1F, which would match 1925 for 11th hottest in the full threaded record and make it the hottest since 1943 in the threaded record.

Up to 72.9F on the month at PIT for the mean temperature, matching 1994 as the highest in June since 1967 (73.0F) and surpassing last year’s final average by 0.1F. Pretty impressive turnaround considering the cold start to the month - we had accumulated an aggregate deficit of 22F from the normal value in just the first 2 days of the month.

Made it down to 69F before midnight standard time, which was also today’s low. Although only at 9 in a row, I’m interested in seeing how many 80+ days we string together. Seemingly no end in sight, though. Strung together 37 in a row in 2020.

Certainly, keeping a close eye on the temperatures here as we close out the books on the month of June. It looks like June 2025 will go down in the weather annals as one of the hottest on record. In Southeast Michigan, it looks like Flint and Saginaw will see top 10 heat, and Detroit should finish up around that number in the means when all is said & done. Same with nearby Lansing, where threaded climate records extend back to 1863. In Saginaw, this could be the 2nd hottest June since 1949 (behind only 2005) if current forecasts hold! Final June 90F count should be interesting as well. Detroit is up to 4 on the month - can they reel off a couple more? In @Spartmanland, Dayton is up to 6, all in a row. Today should make that 7 in a row, and there's a chance for one or two more before the month is through. Haven't seen more than 7 90+ days at Dayton in the month of June since 1994. I know @Spartmanis a big 90-degree enthusiast, and hater of clouds, rain and sub-90 degree readings, so he must be loving this stretch. Suffice it to say, 2017's disastrous 3-day total will not be repeated in 2025.

Let's look at May 2025: xMacis reveals three NOAA stations in Chester County, with a mean temperature of 61.5F. So it's true that the reported mean temperature is higher than the mean of these three stations. But the opposite is true in just about every other county in Pennsylvania.

@chubbs - this is all a bunch of subterfuge. In the vast majority of cases, NOAA systematically reduces the reported temperatures from the observed temperatures on a county-by-county basis, often in ways that make little logical sense. Chester County may very well be the only county in Pennsylvania where the opposite is true. So if there is a conspiracy, it's in the opposite direction as the one presupposed with this analysis.

Daily record high minimum of 77F tied yesterday in Chicago. 000SXUS73 KLOT 270642 RRARERORDRECORD EVENT REPORTNATIONAL WEATHER SERVICE CHICAGO IL142 AM CDT FRI JUN 27 2025...RECORD WARM LOW TEMPERATURE TIED AT CHICAGO-OHARE...A RECORD WARM LOW TEMPERATURE OF 77 WAS TIED AT CHICAGO-OHARE YESTERDAY, JUNE 26, 2025. THE EXISTING RECORD WAS SET IN 1931.$$

Oh, well, technically off, then. This stretch *matches* the longest since 2020. Honestly, I forgot about those. I thought the June heat wave was 4-day stretch and 5 out of 6 days, but it looks like that hot spell was technically an 89, followed by 2 90s, then another 89, and then 3 90s. And then I guess there were 5-day stretches in both July and August last year, which clearly didn't garner as much publicity as the June heat wave. Granted with the two 89s in the mix, there were likely parts of the area (downtown, some valley locations) that may have seen 7 days in a row but without an official reading.

Incidentally, this was probably the largest outbreak of Weathergamis since this has been tracked [which admittedly has only been a couple of years]. A significant number of weathergamis spread from the Plains into the Upper Midwest and Upper Great Lakes, driven by unprecedented low temperatures. Several sites had record high minimum, which by definition will yield a weathergami. Many other stations had low temperatures that have only occurred a handful of times in recorded history and were paired with high temperatures never before seen. Then, this shifted over to New England and the Mid-Atlantic Coast. Over northern New England, high temperatures reached levels seldom ever achieved, and paired with low temperatures that they had never before been paired with. In the Mid-Atlantic, the weathergamis were driven by a mix of unusually high maximum and minimum temperatures, leading to unique pairings. An interesting way to look at this hot spell.

While it may not have reached 100F officially at the Park, the 99/81 was the first day in recorded history with that specific high and low. A weathergami!

1954 had at least a brief shot of extreme heat as well, but maybe it didn't reach all the way to the coast. I know Ohio and western Pennsylvania had 99-100+ temperatures widespread on the 14th. Typically, the coastal Plain is several degrees (3-6F) warmer during hot spells, but maybe the air mass petered out. I believe those heat waves were enhanced by drought in the middle of the country as well, similar but not as extreme as the 1930s drought.

I think 1936 sort of gets a pass because people see all the all-time records (including state records) that extend all the way to the East Coast, but it really wasn't that hot of a summer for most areas in the overall means.

Another interesting thing, seeing 1936 on that list. That really jives with my research. They claim 1936 is the hottest summer on record, tied with 2021. But it looks like it was overall quite cool for most of the eastern United States. Except for that record heat wave that lasted about a week in July, I'd even say downright chilly. Overnight low temperatures were impressively cold in much of rural Pennsylvania that summer. Without that brief stretch, it looks like it would have been one of the coldest on record in many places. Quite odd that it is tied with 2021 for hottest on record. If you look into the numbers, the heat was driven by ridiculously high 12F anomalies (on the plus side) in states like North Dakota and South Dakota where nobody lived in 1936 (and still few reside to this day). I wonder how much the loss of crops and at least temporary desertification played a role in amplifying those numbers. They adjust for "urbanization" but don't make any adjustment for the massive amounts of irrigation and the unnatural density of corn and soybeans across the Plains and Midwest. Without the UHI adjustments, I bet 2021 would take the crown, and some other recent summers would surpass 1936 as well. Also, not saying they should make any crop-based adjustments, but it does strike me as odd how certain human-caused environmental changes are factored in, but others are not.

Very interesting. If you look at the U.S. national temperature records, 1950 was the coldest year overall since 1929, culminating in all-time record cold and snowfall in late November. But 1951 was even colder, reaching temperatures that have been surpassed on the cool side only twice since (1978 & 1979). The winter of 1950-1951 remains the snowiest on record at Pittsburgh. I wonder if the massive Chinchaga firestorm in British Columbia played a role in that impressive national cool spell. You should look at "Black Sunday" in September. Temperatures in the 40s and pitch blackness. We really hadn't seen anything like that again until 2023. Fortunately, it's looking like the Canadian smoke situation has tampered down for the time being, so, hopefully, that won't have a big impact on temperatures the rest of this summer.

Another 90 in the bag… 5 straight. That is the longest since an 8-day stretch ending July 10, 2020.

Looks like a mostly pleasant summer outside of a 5-day heatwave in late August, which, to be honest, was probably urban heat island related anyways. Isn't that the usual explanation for heat extremes these days? Certainly, seems suspect that the Central Park readings went from among the highest in the CWA to among the lowest in the recent heat wave. In 1948, the first 24 days of August, prior to the heat wave, were pleasantly cool. The mean temperature for that stretch being 72.5F, which has been surpassed on the cool side only three times since (1962, 1992, and 2000). The average high temperature, a chilly 79.2F. High temperatures that have only been seen once for that period since (2000). A true summer of yesteryear.

What a joke… the climate report has 93/51 for Boston. Absurd.