TheClimateChanger

What are the stations in each year?

I didn't look at Pennsylvania's Division 3 [Southeastern Piedmont] but I did notice the most recent Julys were showing lower on NCEI's Climate at a Glance than the published figures.

Well, at least for Pennsylvania's Division 9, I don't see that trend. Since 1957, 54 years show a cooling adjustment, 10 warming, and 2 years are exactly the same as published. To be honest, the warming of the 1980s appears to be an artifact of a pairwise homogenization adjustment - perhaps some sort of preferential treatment is given to first order stations. It looks like PIT had a warm bias, so the numbers were adjusted upwards a bit to fall more in line with PIT. The adjustment probably should be in the opposite direction, as the mean value is probably inflated from the apparent warm bias. Which is likely partially due to the HO-83, although the warm bias seems to predate its installation. Some of the recent Julys (2020 & 2021) have among the largest "chilling" adjustments.

I pulled all of the published numbers for Division 9 since 1957 for the month of July, which is when they began publishing in the current divisional format, and there is basically no difference in trend from the published numbers and the values reported on NCEI's Climate at a Glance. I don't see the big warming of recent data that you claim in these values, or in the Chester County May temperature figures you gave above. The earlier years are subject to some adjustment, most notably for Time of Observation bias, but I don't see a big nefarious warming of recent years? Climate at a Glance - Pennsylvania's Division 9 Original Published Values in Climatological Data - Pennsylvania's Division 9 Pittsburgh International Airport

Looks like they mostly resolved the UHI at MSP. It's been running middle of the pack at least for daytime temperatures compared to the region. Used to be 2-3F warmer than most sites.

It looks like @ChescoWx's claim is only true when you include data from personal weather stations and recently opened mesonet sites in the mix, but if you compare the actual divisional means from the reported observation sites, I'm having a hard time finding these big warming adjustments that are often claimed?

Compare this to 1988. The reported value is chilled only 0.3F, versus 1.3F for 2020. And we can see the impact of faulty thermometers (HO-83) with PIT showing a huge warm bias in that era, with temperatures matched only a couple of lock & dam sites [at the lowest elevations of the region].

I have no idea what's going on with the Southwestern Plateau data. I was looking at different years and it's typically chilled, but it used to be less of a chilling. Recent years have been heavily chilled. And it makes zero sense. There are more stations now, with more high elevation sites. There is no longer a city office, which ironically is the source of historic "official" records, but it was a HUGE warm outlier - typically 2-4F warmer than lower elevation sites. And there were fewer stations being averaged then, so it would warm bias the mean. The reasonable conclusion is past temperatures ought to be chilled more than current temperatures, but recent years show the exact opposite. It looks like whatever adjustments are being made are obscuring the warming trend, and then liars are making the exact opposite claim.

Same story in @ChescoWx's neck of the woods. Not as bad, but the observed mean of 79.3F gets artifically chilled to 78.8F.

One thing that's come to my attention. There's this meme that NOAA is jacking up the recent raw temperatures promoted by individuals like @ChescoWx. This appears to be a total fabrication. In fact, when I examine the raw data and compare it to the reported values, there is a significant chilling effect being introduced to observed temperatures. For instance, here is the observed data for the Southwest Plateau division of Pennsylvania in July 2020, showing a mean of 76.3F. This would easily break the record for the month of July. But if you look at Climate at a Glance, it's been chilled all the way down to 75.0F!

Your neck of the woods was highlighted in the National Climate Assessment as facing one of the highest increases in relative fire danger. Those marginal boreal forests are especially at risk with species like aspen and balsam fir, which are well adapted for a cooler, wetter climate. The Trump administration wants to increase logging on public lands, including a number of the forests up there. Probably not a bad thing to provide fire breaks and facilitate the transfer of new species from forests further south.

Low of 70F at INL this morning, which will easily surpass the monthly record high minimum of 66F set on 5/21/1992 & 5/31/1988. In fact, it's only one degree shy of the June monthly high minimum of 71F set on 6/25/2001. With that said, it is possible that it may fall below 70F by 1 am CDT / midnight CST, but it should stay above 66F. The forecast low tonight is 64F at INL.

Even excluding today's 99F, the mean high temperature at Grand Forks was running as 8th warmest on record for the first 10 days of the month. This is an interesting set of analog years. Not sure it means much, but 1934, 1936 & 1988. Even 1980 & 1977 had some big heat. The two most recent years on the list don't follow, however - especially 2023.

Stalled out after the 12:53 pm CDT observation, which is really before local solar noon during daylight saving time. Thought they would climb to at least 101 or 102, after rising 39F already by that point of the day. There were monthly record highs at several locations, including International Falls, which reached 96F, beating out the record of 95F from May 21, 1964. Minot, ND reached 99, matching the value reached on May 22, 1980 at the airport. While not a ThreadEx location, it does look like the NWS does an unofficial thread supplying records prior to 1948 from the Experimental Station where there were a couple of higher values (100 on May 23, 1928 & 105 on May 31, 1934). Could see some monthly record high minimums tomorrow at several locations as forecast lows for tonight are close to the highest observed in the month of May, including International Falls where the forecast low of 66F would tie the monthly record high.

Impressive heat in the upper Midwest. Up to 99F as of 1 pm at Grand Forks, North Dakota. Should have no problem clearing 100+, which would be the second earliest on record. The earliest 100+ reading occurred on April 21, 1980. There have only been 3 days in the month of May at or above 100F in recorded history at that location: 101F on 5/21/1964; 105 on 5/30/1934; and 100 on 5/30/1939. The monthly record high of 105F is probably safe, but I could see the high ending up between 102F and 104F with 2-3 hours of heating possible, so it could make a run for it. At Grand Forks, there have been a total of 62 days at or above 100F recorded since 1893. If it gets above 102F, that would be pretty rarified air for any time of the year. There have only been 20 days above 102F, of which 8 occurred during the summer of 1936, which was particularly harsh in that region.

A touch of frost on my roof earlier, but that was it. Low of 36 on my weather station. Otherwise, looks like a beautiful weekend for a change. Trey from KDKA did note a little wildfire smoke might make things a touch hazier tomorrow morning, but doesn’t look like it should be too thick by the time it reaches our latitude.

Here is LaGuardia. Regression shows an increase from 10 days of 90+ to 25 days of 90+ since 1960. The peak 5 year moving average was 31 in 2022 - just two summers ago. It's fallen back a small bit over the last 2 summers, but a particularly hot summer this year will likely send it back to a new record 5 yma.

I'm not sure I buy that. The 5-year moving average for Newark is up to 37 days of 90+ which is the most on record, matching the 5 yma from 1995 [which I have previously explained why the numbers from that era were inflated at first order sites, but everyone here just ignores that fact?]. A regression since 1960 suggests an increase in 90+ days of nearly two weeks over that time period - from 20 to 33 days. Central Park is the only site that seems to be bucking that trend, but I think @bluewavehas extensively documented the impact of overgrown vegetation surrounding the ASOS site and significant shading of the ASOS.

I don't think so. Just last summer was the most 90+ days since 1995 at Pittsburgh (24). Humidity is WAY up and average July lows have climbed up about 3-5F just in the past 3 to 4 decades.

I tend to think July 2020 was the worst of my lifetime. The mean high temperatures were comparable to 1988, but lows were in the mid 60s at most sites. Just lacked the few days in the upper 90s/low 100s, instead topping off mostly in the mid 90s. Most places did not even have a single night below 55, several did not drop below 60 the entire month. Contrast that to 1988, and most rural/suburban sites had average monthly lows in the 50s.

Sorry but you are wrong. Most sites in southwest Pennsylvania were in the 30s those days. Burgettstown was the coldest location, but there were several others in the mid 30s and several more in the upper 30s on the same date. And it wasn't even the coldest temperature in the State of Pennsylvania that month - two others reached 32F, and one reached 31F. The 49F at PIT was a massive outlier, probably UHI & faulty HO-83 thermometer. In recent years, the statewide low is typically like 40F in July. In 2020, it didn't drop below 49F officially anywhere in the State. You can really see the impact of the airport effect/faulty temperatures in the data from northwest PA that month. Most places had lows in the low to mid 50s, with a few in the upper 50s. Two of the three airport sites were huge outliers... DUJ: 62.1F and ERI: 65.0F, although the latter, of course, was elevated due to the proximity to Lake Erie as well. Not the case with DUJ, which is a relatively high elevation site to begin with (~1,800 feet ASL). It's funny because you are always pretending the airport heat island temperatures are a new phenomenon, when I can look back decades and see there was actually even a larger discrepancy back then versus today.

The average July low is up like 3-5F at all of the airports nearest me since 1990. Like here's a more distant suburb of Pittsburgh in 1988. The low was 35, 32 & 36 on July 1-3, 1988. Does anyone think such temperatures are possible today? The only place where such lows can occur today are places like Canaan Valley, West Virginia, which is an elevated (3-4k) frost bowl. Like this is supposed to be the Hottest Summer Ever (TM) and the average low at this location was a cool 55.7F. That's open window weather. Even on the days of 100F, it cooled down into the 50s and low 60s, enabling efficient cooling by a window fan at night.

84F at Duluth. I think the bigger shocker is the record high for today was an insane 92F (see below). Many places way further south have never recorded such a high temperature this early in the year. The earliest 92F reading at Dayton, Ohio occurred on May 9, 1896. Since 1962, the earliest 92F reading was on May 28, 2012.

Bradford, in the mountains of northern Pennsylvania, warmed nearly 4.5F over the same period.