TheClimateChanger

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.

Northeast Ohio and Northwest Pennsylvania. My memory is well supported by data. Erie lakeshore used to be freezing cold deep into May. A linear regression shows an increase in May high temperatures of nearly 3.5F since 1990, which is a lot more than the Coastal Plain. It's gone from several degrees colder than New York City to only a couple of degrees colder. May high temperatures have barely budged at New York City over the same time period.

It makes a big difference though with air conditioning needs. Just in my lifetime, a linear regression shows an increase in July minimum temperatures of 3 to 4F. But that's just the daily low. IMO, it also cools off more slowly. Whereas in the past, it might reach near the daily low by 1 am and then kind of hang steady, now it's only for a little time before sunrise. I bet 8pm to 11pm temperatures have risen 5F or so.

Actually, I remember going to fireworks and occasionally needing a hoodie at night because it was in the low 60s. You don't need that today, because it's still 70+ at 11 pm.

I was living in the 90s, and I don't recall it as "much hotter." We didn't even have air conditioning in my bedroom. I don't think you could do that today. It doesn't cool down enough at night to open a window.

Yes, overall, that looks like a cool summer. Compared to most modern summers, a summer of yesteryear, no doubt.

I think 1977 is exaggerated or something. It was the second coldest on record at Pittsburgh, behind only 1976.

Going to tough to break those inflated numbers from the HO-83 era. Big warm bias at the first order sites.

Wow, JB doesn't seem to understand the difference between an ice sheet and sea ice. Odd.

Not sure I buy that. It looks like a 5-period moving average is near the maximum for 90-degree days at both LGA and EWR, with the LOESS curve predicting the highest value of 90+ days in the POR at both sites. Looks like we are on the precipice of a big upswing in heat. Even a small additional increase in 90+ days would likely push your area outside of historic norms. Also, as I have noted numerous times, the heat spike from 1986-1995 very likely an artifact of the data collection due to the defective HO-83 sensors in use during that brief era. The increase in 90+ days matches up temporally with the proliferation of HO-83 units. After installation of ASOS, the 90+ days rapidly drop back to pre-1986 levels, from which they have since steadily climbed. The impact of the HO-83 cannot be dismissed a small bias. It was a substantial bias, the magnitude of which varied by site. At Lincoln, Nebraska, it averaged nearly 2F warmer than the ASOS, although at times, it could be as much as 7F warmer. See: Central Region Technical Attachment 93-07, Comparison of ASOS and HO83 Temperatures at Lincoln, Nebraska from November 1991 through October 1992, George H. Grosshans, NWS Lincoln (1993).

Through yesterday, this has been the sixth warmest spring to date. By my calculation, May would need to finish with an average temperature of 68.1F to tie the record for warmest spring (set in 2024). Currently, the month to date is at 65.4F. We will lose some ground this week; however, there are some indications of a warmer weather pattern by the middle of the month. Either way, a top five warmest spring season is looking increasingly likely.

Spartaman is not going to like the Old Farmer’s Almanac outlook for the summer. Hot and dry pretty much everywhere, except in Ohio and surrounding areas. At least it’ll still be hot - although with all that rain, you have to assume it would be more from warmer minimum temperatures.