TheClimateChanger

And for Pocopson, in Chester County, he had 21 years of data [1853-1873]. Mean annual temperature was 51.9F, ranging from 49.9F in 1868 to 54.7F in 1853. Unfortunately, this data set ends before the very cold year of 1875. Regardless, I feel like these temperatures are lower than anything reported in recent decades.

How do your records compare to those published in Lorin Blodget's seminal work on the Climate of Pennsylvania, published in 1889? He had 33 complete years of data for West Chester from 1855-1887, plus all of 1888 except for December, and computed an annual mean of 51.3F, ranging from a minumum of 47.8F in 1875 to a maximum of 53.7F in 1870.

Maybe I'm off base here, but, to me, it always seems the urban heat island effect is blown way out of proportion. Sure if you're measuring temperatures in a dense city, particularly over a dark rooftop or asphalt, it's going to be somewhat higher. But other than that, there doesn't seem to be any strong relationship between temperature and population. Just look at the temperatures this month around here, where is the urban heat island effect? PIT: 54.4F [Allegheny Co., pop: 1.25M] [Elev: 1201 feet] [lat: 40.50N] PHD: 54.0F [Tuscarawas Co., Ohio, pop: 93K] [elev: 892 feet] [lat: 40.47N] ZZV: 54.2F [Muskingum Co., Ohio, pop: 86K] [elev: 899 feet] [lat: 39.94N] DUJ: 53.4F [Jefferson Co, Pa., pop: 44K] [elev: 1804 feet] [lat: 41.18N] HLG: 55.8F [Ohio County, W. Va., pop: 42K] [elev: 1194 feet] [lat: 40.17N] MGW: 56.5F [Monongalia Co., W. Va., pop: 106K] [elev: 1227 feet] [lat: 39.65N] JST: 52.9F [Cambria Co., Pa., pop: 133K] [elev: 2274 feet] [lat: 40.31N] AOO: 55.0F [Blair Co., Pa., pop: 123K] [elev: 1467 feet] [lat: 40.30N] Here is data from the second most populated county in Pennsylvania, at the second busiest international airport in the State, versus data taken from a bunch of small airfields in mostly rural counties. Where is the urban heat island effect in this data? Almost like temperature varies by latitude and elevation, and not by population.

Just had a brief snow shower here.

I noticed PIT reported some flurries late this morning. I also noticed some frozen precipitation around that time as I was doing yard work, but I couldn't tell if it was light ice pellets or snow flurries - the precipitation was very light, and did not last long.

7th 80+ at BFD today. Previously, the earliest date on which 7 80+ readings occurred in a calendar year was May 19, in 1962.

What location do you guys think is warming the fastest due to climate change? I've noticed Burlington, VT seems to be getting hit particularly hard. The current climate there is about on par with what was common in the lower Great Lakes in the late 19th century - early 20th century. But it used to be very, very cold there. Since 1960, a linear trend line estimates warming at over 9F per century - or just shy of a degree each decade. Again, in the last 5-10 years, the rate of warming seems to be increasing with an abundance of years above even this drastic trend line.

Bradford notched its sixth 80+ reading of the month (not reflected on graphic below), adding to its record-breaking monthly total. Looks like a seventh on tap for tomorrow. To put that into perspective, there have been 21 Julys (out of 64 years) with 7 or fewer 80+ readings at Bradford. So roughly 1 in every 3 Julys has fewer 80+ degree days than this month.

Even if true, what difference does that make when you've offered no proof that rural locations are cooler or warming less? Here are several examples - zero evidence that the trend is any different for the rural locations than the urban locations. Bradford, PA [McKean Co. population: 40k] - warming at 5.6F/century since 1958 Elkins, WV [Randolph Co. pop: 27k] - warming at 5.7F/century since 1958 DuBois, PA [Jefferson Co. pop: 44k] - warming at 4.4F/century since 1963 [no earlier data] Morgantown, WV [Monongalia Co. pop: 105k] - warming at 4.9F/century since 1958 Pittsburgh, PA [Allegheny Co. pop: 1.25M] - warming at 5.1F/century since 1958

Yes, I took a look at this recently and couldn't find any evidence of an urban heat island effect when comparing Pittsburgh to a few small towns in the northern Appalachians and Allegheny Mountains. Probably most alarming is the warming is approaching 6F per century, but it's actually accelerating rapidly (evidenced by the fact that recent years are almost exclusively above what would be predicted by the linear trend line). Since 1958, Elkins, WV has warmed at 5.7F/century. The population of Elkins is 6,950, and Randolph County is 27,932 as of the 2020 census. Since 1958, Bradford, PA has warmed at 5.6F/century. The population of Bradford is 7,849, and McKean County is 40,432 as of the 2020 census. Since 1958, Pittsburgh, PA has warmed at 5.1F/century. The population of Pittsburgh is 302,971, and Allegheny County is 1,250,578 as of the 2020 census. Since 1963, DuBois, PA has warmed at 4.4F/century. The population of DuBois is 7,510, and Jefferson County is 44,492 as of the 2020 census. DuBois is located in Clearfield County [pop: 80,562], but the airport is in Jefferson County. I can't see an urban heat island effect in this data. These are pristine mountain towns surrounded by national and state forests and park lands - some of the most rural areas east of the Mississippi River. Much, much more rural than Chester County, PA [pop: 534,413], which is the 7th most populated county in the State of Pennsylvania.

Don, I think what’s even more concerning than the fact it’s warming at a rate of 5-6F/century over the last 65 years at these locations is the fact that, looking at the data, it’s clear there’s an accelerating increase. If the linear trend line was actually explaining all of the trend, you’d expect data points to be distributed equally above and below it throughout the period covered by the trend line. Instead, in recent years, the vast majority of temperatures are exceeding what would be predicted by the linear trend. Looks like we may be warming at an instantaneous rate of 7 or 8 degrees per century now. But it would take a couple decades to confirm that.

Interesting, I decided to take a look at this phenomenon with an open mind and selected three remote, rural towns in the mountains mostly surrounded by state and national forest and parkland. And compared them to the records at nearby Pittsburgh. Can't find any evidence of an urban heat island amplifying the warming at Pittsburgh. If anything, as I surmised, the rural locations look to be warming slightly faster. Here is the comparison. All since 1958, except for DuBois [where records extend only to 1963]. Rounded to the nearest tenth of a degree, I found Bradford to be warming at 5.6F per century; Elkins warming at 5.7F per century; Pittsburgh warming at 5.1F per century; and DuBois warming at 4.4F per century.

Very impressive, Don. I noticed Bradford, PA reached 86F / 30C at over 2100 feet of elevation, setting a new monthly record (after tying the record of 85 yesterday which was set last year and twice in 1990). There are many years in Bradford where the thermometer has failed to reach 86F / 30C over the entire year. If that had mixed down to the surface, I think we would have been looking at widespread low to mid 90s in the lowlands, with maybe upper 90s in the urban corridor. As an aside, I feel it weird many people say urban heat island effect is responsible for all or part of the warming trend. To me, anyways, it feels like the remote forested mountain locations like Bradford, Pa. are warming faster than anywhere else in recent years. Just not seeing much evidence of an urbanization effect on the trend.

Yeah, awful around here too. Never seen this in April. Must be the mild winter. Kind of related, but I was reading the Lakes & Midwest forum and someone from Minnesota was noting the start of tick season. I wish we had a no-tick season in this subtropical wasteland of a state. My dog was coming out of the woods just covered in those nasty things all winter long.

Bradford reached 86 degrees today, setting a new all-time April record high. There are many years where it doesn’t even reach 86 all summer long in Bradford. The airport is at 2106’, not far from the NY line. If we had mixed all the way to that layer, we would have been looking at widespread low to mid 90s today in the lowlands.

Bradford reached 85, tying the all-time record for the month of April, set previously on April 24, 2022, April 27, 1990, and April 28, 1990.

Given there was essentially no change to the annual means from the site change, this is a particularly interesting analysis: Last year with annual mean below 44: 1917 [43.7F] Last year with annual mean below 45: 1926 [44.3F] Last year with annual mean below 46: 1943 [45.6F] Last year with annual mean below 47: 1996 [46.9F] Last year with annual mean below 48: 2014 [47.2F] I think it's safe to say it's impossible at this point for Buffalo to have an annual mean below 46F, and probably not too far off before we can say the same thing for 47F. Already been 27 years since the last sub-47F annual mean; however, it was only a couple of tenths warmer just 9 years ago. So I don't know if it can be completely ruled out.

Also, there was no change to the annual mean temperature [less than a 0.1F increase]. So the annual means are directly comparable between the sites with no adjustments needed. The airport has mean high temperatures about 2 degrees warmer than downtown, but mean low temperatures about 2 degrees cooler than downtown. Buffalo Airport Buffalo Downtown Difference 1939 56.1 54.4 1.7 1940 53.7 52.1 1.6 1941 57.4 54.8 2.6 1942 56.3 53.7 2.6 1943 54.8 52.8 2 Avg 55.66 53.56 2.1 Buffalo Airport Buffalo Downtown Difference 1939 38.5 41 -2.5 1940 36.7 39.1 -2.4 1941 39.2 41.8 -2.6 1942 39.5 41 -1.5 1943 37.7 38.7 -1 Avg 38.32 40.32 -2 Buffalo Airport Buffalo Downtown Difference 1939 47.3 47.7 -0.4 1940 45.2 45.6 -0.4 1941 48.3 48.3 0 1942 47.9 47.3 0.6 1943 46.3 45.7 0.6 Avg 47 46.92 0.08

Not much of a change over the six Marches with overlapping records at the two sites. The downtown site had a mean maximum of 36.7, versus 37.6 at the airport. Buffalo Downtown March 1939: 36.9 1940: 33.0 1941: 32.4 1942: 42.1 1943: 38.3 1944: 37.2 6-year average: 36.7 Buffalo Niagara International Airport March 1939: 38.0 [+1.1] 1940: 32.3 [-0.7] 1941: 34.5 [+2.1] 1942: 42.4 [+0.3] 1943: 39.8 [+1.5] 1944: 38.5 [+1.3] 6-year average: 37.6 [+0.9]

That would be an average (arithmetic mean) high. Normal highs are smoothed or "normalized" throughout the calendar year to produce a continuous pattern of rising or falling temperatures.

Well, even the temperatures observed by the U.S. Army Signal Corps back in the 1850s and 1860s seem crazy by today's standards. The average annual mean temperature was observed to be 46F at Buffalo, 47F at Detroit, 47F at Erie, 48F at Chicago, 50F at Pittsburgh, and 52F at Philadelphia. What was considered to be the mean temperature in that era would be top ten coldest on record since 1870s at Detroit and Erie, top twenty coldest at Chicago and Buffalo, and top five coldest at Philadelphia. Not as bad at Pittsburgh, but still a couple degrees cooler than the modern mean observed at Pittsburgh Airport [51.8F], which is at 1200' elevation; whereas the 50F mean determined by the Signal Corps was observed at Fort Pitt, which is identified as 704' in elevation [or a full 500' lower in elevation]. For context, the average lapse rate is something on the order of 3.5-5.4F/1000 feet, and the calculated difference between the city office and the airport was 2.6F during the period of overlap [1952-1979], which would imply the city mean would be 54.4F today - or in line with the changes at the other sites.

With a little help from Dall-E:

It's not cherry-picking. I used all of the 19th century data available for each site - generally between about 27 and 30 years [30 years being a full climatological period], and compared it to the data since the beginning of the last decade. I did check the numbers with data for 2000-2009, and incomplete data for 2023, and it only decreases a small amount. You are welcome to run the analysis yourself. Average high temperatures were selected to minimize effects of urban heating - which is much more pronounced in the overnight minima. Second, the first skyscraper wasn't even built until 1885. Most weather data was collected on low rise buildings in that era, no more than 100 feet or so above street level - typically even less. Anthony Watts, et al. has shown that rooftop temperatures have a massive warm bias compared to readings taken at ground level. See: https://wattsupwiththat.com/2008/01/23/how-not-to-measure-temperature-part-48-noaa-admits-to-error-with-baltimores-rooftop-ushcn-station/. Look at the data he presents for Baltimore Custom House (a rooftop site) compared to the ground-level readings at Baltimore Harbor. The rooftop site had 81 days of 90+ (including 13 days of 100+), while the ground site had only 38 (and none at or above 100). So, if anything, these early rooftop readings are likely WAY too high, not too low.

At some of these locations, typical 19th century March high temperatures are rarely if ever experienced. Since 1990, MKE has seen a March with an average high temperature below the 19th century mean only twice (2013, 36.0 & 2014, 36.7); DTW once (2014, 37.6); ORD, twice (2013, 39.6 & 1996, 40.2); DCA, once (1993, 49.9); NYC, none; and PHL, once (1993, 47.0). In other words, the coldest Marches of some of our lives would have been considered normal weather in the 19th century.

Decided to quantify the changes in early spring temperatures by comparing the average March high temperatures in the late 19th century to the most recent 13 years (2010-2022). I used average high temperatures to somewhat minimize the impacts of urban heat island effect. What we can see are absolutely prodigious changes. Large cities in the lower Great Lakes (Cleveland, Detroit, Chicago, Buffalo) experienced 19th century early spring temperatures which were generally cooler than Green Bay, Wisconsin in the most recent 13 years (41.6F). In the case of Buffalo, as well as cities like Minneapolis and Milwaukee, March high temperatures in the 19th century are about equal to (or in the case of MSP) cooler than recent average March high temperatures at places such as Duluth (37.1F) and International Falls (37.4F), and only a couple of degrees warmer than average March high temperatures at Caribou, Maine in the most recent 13 years (34.8F). March high temperatures in New York City during the late 19th century are cooler than recent readings in places such as Milwaukee, Minneapolis, Buffalo and Rochester, and only a couple degrees warmer than recent readings in Green Bay, Wisconsin. By comparison, recent March high temperatures in New York City are about a degree warmer than what was observed in Washington, D.C. in the 19th century. March highs in Pittsburgh, as well, are now 0.6F warmer than D.C. in the late 19th century. Washington, D.C. on the other hand is seeing March high temperatures today only a couple of degrees cooler than places such as Raleigh/Durham and Charlotte, North Carolina experienced in the 19th century. Philadelphia had cooler March highs in the 19th century than places such as Cleveland, Detroit and Chicago. Today, Philadelphia sees March high temperatures which exceed those measured in Washington, D.C. in the 19th century by several degrees. Generally, northern locations have warmed from 5-8F over that timeframe, while southern locations have warmed from 4-5.5F. These temperatures correspond to climate shifts of hundreds of miles. I think if you teleported someone in from the 19th century, they would be very confused by these changes - maybe even moreso than they would be of all the technological changes. Here is what I found: Milwaukee, Wisconsin 1871-1900: 37.1F 2010-2022: 44.1F (+7.0F) Detroit, Michigan 1874-1900: 39.7F 2010-2022: 47.4F (+7.7F) Chicago, Illinois 1873-1900: 40.9F 2010-2022: 47.6F (+6.7F) Cleveland, Ohio 1872-1900: 40.9F 2010-2022: 48.2F (+7.3F) Minneapolis, Minnesota 1873-1900: 36.7F 2010-2022: 43.3F (+6.6F) Buffalo, New York 1874-1900: 37.3F 2010-2022: 43.4F (+6.1F) Rochester, New York 1872-1900: 37.6F 2010-2022: 44.6F (+7.0F) Erie, Pennsylvania 1874-1900: 40.3F 2010-2022: 45.2F (+4.9F) Pittsburgh, Pennsylvania 1875-1900: 47.6F 2010-2022: 50.8F (+3.2F) Keep in mind at Pittsburgh, this is comparing downtown records (elevation: 780-800 feet) to airport records (elevation: 1200 feet), and about 15 miles northwest, which hides a lot of the warming trend. Washington, D.C. 1872-1900: 50.2F 2010-2022: 57.6F (+7.4F) New York, New York 1869-1900: 43.4F 2010-2022: 51.0F (+7.6F) Boston, Massachusetts 1872-1900: 42.0F 2010-2022: 46.9F (+4.9F) Philadelphia, Pennsylvania 1874-1900: 47.2F 2010-2022: 53.8F (+6.6F) Atlanta, Georgia 1879-1900: 61.1F 2010-2022: 66.5F (+5.4F) Memphis, Tennessee 1879-1900: 60.6F 2010-2022: 64.8F (+4.2F) Raleigh/Durham, North Carolina 1887-1900: 59.1F 2010-2022: 63.5F (+4.4F) Charlotte, North Carolina 1879-1900: 59.9F 2010-2022: 65.1F (+5.2F)