ChescoWx

A nice cool morning with the lowest I could find being the 49.6 at Warwick Township. A beautiful day today with highs in the mid 70's. Another cool day tomorrow before the warming trend kicks in on Wednesday with the warmest day being Friday with temps near 90 degrees. We cool back a few degrees by next weekend but still above normal. Chester County records for today: High 102 degrees at Phoenixville (1933) / Low 37 degrees at Coatesville (1972) / Rain 3.67" at KMQS Coatesville Airport (2013)

So are the nights getting warmer in the Philly burbs (I actually thought they would show this) but as with all of the temperature analytics - very cyclical with a cooling trend in excessively high nighttime lows over the last 2 complete decades.

Hey GaWx See the below with # of average lows by station over 75 degrees since 1900....a bit surprising to me but as with most of our metrics - very cyclical with a clear trend to less warm nights over the last 2 decades.

Hey GaWx that would be a interesting I would suspect that in our current warming cycle while our Tmaxes are lower the Tmins should be higher as our climate variation seems to be narrowing during this latest warming cycle. I will run some analysis! Thanks!!

I was asked to also look at hot days >95 degrees over the same time frame. Plus I added in the average number per station as the number of stations have changed by decade with a dramatic increase in stations in the 2010's . Again the hottest decades were as we all know back in the 1930's thru 1950's.

I was asked to also look at hot days >95 degrees over the same time frame. Plus I added in the average number per station as the number of stations have changed by decade with a dramatic increase in stations in the 2010's . Again the hottest decades were the 1930's thru 1950's.

Below is an analysis of 100 degree days by Decade. Not surprisingly about 50% of these extreme hot days all occurred between the 1930's through 1950's. We have noted a sharp decline in these type of extreme heat days across the County. So far in the 2020's only one such day here in Chesco back on August 23, 2021.

Some have asked how many so far here in the 2020's?? Answer only 1 back on August 23, 2021 at West Chester PA

Thanks! looks very cyclical as our climate change always is and will be!!

Below is an analysis of 100 degree days by Decade. Not surprisingly about 50% of these extreme hot days all occurred between the 1930's through 1950's. We have noted a sharp decline in these type of extreme heat days across the County.

A slight chance of a shower this morning then sunny breezy and continued pleasant weather. We start to warm up by the end of the week with some spots possibly hitting 90 degrees for the first time this season by Friday. Chester County records for today: High 102 in Phoenixville (1933) / Low 38 degrees at Devault (1957) / Rain 2.72" at West Grove (1955)

All spots fell into the 50's this morning with the lowest temp the 52 degrees at Nottingham. A beauty of a day on the way with comfortable humidity and temps well into the 70's in higher spots and low 80's in the valleys. A reinforcing weak cold front will cross the area tomorrow which may induce the only shower chance for the next week. Chester County records for today: All the records for today occurred in Phoenixville: High 104 degrees (1925) / Record Low 39 degrees (1949) / Rain 4.37" (1938)

All spots fell into the 50's this morning with the lowest temp the 52 degrees at Nottingham. A beauty of a day on the way with comfortable humidity and temps well into the 70's in higher spots and low 80's in the valleys. A reinforcing weak cold front will cross the area tomorrow which may induce the only shower chance for the next week. Chester County records for today: All the records for today occurred in Phoenixville: High 104 degrees (1925) / Record Low 39 degrees (1949) / Rain 4.37" (1938)

With the frontal passage last night and a couple more over the next few days we should see a great stretch of dry and comfortable weather. The only real chance of rain over the next week looks to be late in the day on Sunday. Chester County records for today: High 104 degrees at Phoenixville (1925) and 97 degrees at Coatesville in 1899 / Low 37 degrees at Phoenixville (1945) / Rain 4.19" KMQS Coatesville Airport (2013)

With the frontal passage last night and a couple more over the next few days we should see a great stretch of dry and comfortable weather. The only real chance of rain over the next week looks to be late in the day on Sunday. Chester County records for today: High 104 degrees at Phoenixville (1925) and 97 degrees at Coatesville in 1899 / Low 37 degrees at Phoenixville (1945) / Rain 4.19" KMQS Coatesville Airport (2013)

Let's start this baby off for those of you interested in actual factual climate for our area!! Thanks again!!! Below is a chart splitting the Chester County PA Climate Period between almost down the middle since 1895. We have 64 years climate averages by month from 1895 thru 1959 with a comparison to the most recent average temperatures for the 63 year period from 1960 thru 2023. The top (Grey) includes all 27 Chester County stations (even those introduced with modest relative elevation increases). The next section (Yellow) shows the adjusted NOAA/NCEI Altered Adjusted Data. The bottom (green) only includes the 17 stations at a similar relatively lower elevation. Not surprising across all of the actual data there has been essentially no change in our average annual temperatures over the last 63 years vs. the prior 64 years. The only way we get any warming (+1.2 degrees) at all to appear is to apply the post observation adjustments to the data (as shown in the altered data in yellow). Of most interest overall Januaries have trended colder and Decembers warmer but all other months only show slight variations over the split climate periods of record.

I thought I would start a unique thread specific to the Philadelphia Mount Holly Zone for those of you that have any interest in this kind of long term climate data. That said I wanted to respect those of you who wish to avoid this kind of long term climate analysis which due to our limited years of data will often lead to debate you may wish to avoid! If this kind of longer term Climate Data Analytics is not your cup of tea...please avoid this thread as many on both sides of the debate view this topic sort of like a religion! But if you like so many folks on this forum seem to enjoy and learn from this kind of real world climate data and analytics please feel free to post here. But please if you post here....be sure to come forward with your data to support your position as folks on this thread are more interested in facts over what you feel the climate might be perceived to be doing here in the Philadelphia / Mount Holly Zone !! Thanks to all of you!!!

Below is a chart splitting the Chester County PA Climate Period between almost down the middle since 1895. We have 64 years climate averages by month from 1895 thru 1959 with a comparison to the most recent average temperatures for the 63 year period from 1960 thru 2023. The top (Grey) includes all 27 Chester County stations (even those introduced with modest relative elevation increases). The next section (Yellow) shows the adjusted NOAA/NCEI Altered Adjusted Data. The bottom (green) only includes the 17 stations at a similar relatively lower elevation. Not surprising across all of the actual data there has been essentially no change in our average annual temperatures over the last 63 years vs. the prior 64 years. The only way we get any warming (+1.2 degrees) at all to appear is to apply the post observation adjustments to the data (as shown in the altered data in yellow). Of most interest overall Januaries have trended colder and Decembers warmer but all other months only show slight variations over the split climate periods of record.

Quite the spread of rain totals since yesterday with the warm frontal passage with much more across Southwest Chester County with around 4.37" at Nottingham Park to as little as 0.15" at Devault in Northeast Chester County. Very humid this morning before a strong cold front enters the County from West to East around the 3pm till 4pm time frame. A beautiful Friday through most of Sunday with pleasant temps with lows in the 50's and highs in the mid 70's give the AC a rest! Chester County Records for today: Highs 102 degrees at Phoenixville (1925) 99 degrees in Coatesville (1899) in Western Chesco / Low 38 degrees at Coatesville (1958) / Rain 4.80" in West Chester (1928)

Quite the spread of rain totals since yesterday with the warm frontal passage with much more across Southwest Chester County with around 4.37" at Nottingham Park to as little as 0.15" at Devault in Northeast Chester County. Very humid this morning before a strong cold front enters the County from West to East around the 3pm till 4pm time frame. A beautiful Friday through most of Sunday with pleasant temps with lows in the 50's and highs in the mid 70's give the AC a rest! Chester County Records for today: Highs 102 degrees at Phoenixville (1925) 99 degrees in Coatesville (1899) in Western Chesco / Low 38 degrees at Coatesville (1958) / Rain 4.80" in West Chester (1928)

Below is an analysis of Spring (April-May) average temperatures here in Chester County PA from 1895 through this year. Of note the actual temperature trends (Blue) show almost no warming at all... while the NOAA Altered Adjusted data (Red) shows as expected some solid warming.

Showers should hold off till late in the day and arrive across the county from SW to NE this evening. Showers tomorrow will end by evening but some spots could see over an inch or more of rain by tomorrow night. Cooler and drier weather arrives for the weekend with falling back below normal with temps no higher than the low to mid 70's. Below normal temps should continue through the first few days of next week. Chester County Records: High 102 degrees at Phoenixville (1925) and in Western Chesco it was the 97 degrees that same day. Low 39 degrees at Coatesville (1947) / Rain 2.39" Coatesville (1970)

Showers should hold off till late in the day and arrive across the county from SW to NE this evening. Showers tomorrow will end by evening but some spots could see over an inch or more of rain by tomorrow night. Cooler and drier weather arrives for the weekend with falling back below normal with temps no higher than the low to mid 70's. Below normal temps should continue through the first few days of next week. Chester County Records: High 102 degrees at Phoenixville (1925) and in Western Chesco it was the 97 degrees that same day. Low 39 degrees at Coatesville (1947) / Rain 2.39" Coatesville (1970)

Why would they be warming at all during our current warming cycle? They are doing very well at continuing to warm the present!

Yep they warmed 20 of the last 23 years vs. actual see below to it would seem to enhance the warming.. Only those in red were cooling adjustments Year Actual NCEI Altered Adj. 2001 74.3 75.3 1.0 2002 76.1 77.1 1.0 2003 73.0 74.1 1.1 2004 72.3 73.1 0.8 2005 76.5 77.4 0.9 2006 75.3 76.2 0.9 2007 74.5 75.4 0.9 2008 74.8 75.4 0.6 2009 72.9 73.9 1.0 2010 76.8 77.4 0.6 2011 75.4 76.8 1.4 2012 75.2 76.9 1.7 2013 74.2 75.5 1.3 2014 73.9 73.1 (0.8) 2015 74.9 75.4 0.5 2016 77.4 78.1 0.7 2017 74.6 74.7 0.1 2018 75.4 76.8 1.4 2019 76.5 76.3 (0.2) 2020 78.0 78.0 0.0 2021 77.1 77.1 (0.0) 2022 76.8 77.3 0.5 2023 74.8 76.3 1.5