ChescoWx

Of note Spring of 2026 was the 14th warmest Spring since 1893 - conversely Winter 2025-26 was our 14th coldest! Our weather does have a way of balancing out! Below is our Spring Temperature trends since 1893....only some slight warming evidenced by the data.

Since 1893 we have seen a cooling trend during the month of May here in Chester County PA

Of note here in the philly burbs of Chester County PA Spring of 2026 was the 14th warmest Spring since 1893 - conversely Winter 2025-26 was our 14th coldest! Our weather does have a way of balancing out! Below is our Spring Temperature trends since 1893....only some slight warming is shown.

Of note here in the philly burbs of Chester County PA Spring of 2026 was the 14th warmest Spring since 1893 - conversely Winter 2025-26 was our 14th coldest! Our weather does have a way of balancing out! Below is our Spring Temperature trends since 1893....only some slight warming is shown.

Since 1893 we have seen a cooling trend during the month of May

Since 1893 we have seen a cooling trend during the month of May

Below is the May 2026 Chester County Climate Summary. We finished May with an average temperature of 60.8 degrees across all stations. This was 0.7 degrees below the 1991-2020 average May temperature of 61.5 degrees. This was the 56th coldest May in 134 years of records back to 1893.

Below is the May 2026 Chester County Climate Summary. We finished May with an average temperature of 60.8 degrees across all stations. This was 0.7 degrees below the 1991-2020 average May temperature of 61.5 degrees. This was the 56th coldest May in 134 years of records back to 1893.

Today will be the 11th of the last 13 days with below normal temperatures. Sunny and dry through Saturday. We should finally see some warmer than average temperatures by the end of the week and into the weekend. Rain chances look to increase by Sunday.

Today will be the 11th of the last 13 days with below normal temperatures. Sunny and dry through Saturday. We should finally see some warmer than average temperatures by the end of the week and into the weekend. Rain chances look to increase by Sunday.

I am compiling the final averages but it looks like Chester County will finish around a 1 degree below the 1991-2020 average for the Month of May

But of course during that 1978 to 2025 period Phoenixville 1E is warming at almost a 50% faster rate than the rest of Chester County. The Phoenixville area is about as least representative of the entire county with about 60% of Chesco lying at over 400ft above sea level

Lows this morning were not too far from record cold levels for the final day of May. The lowest was the 38-degree reading at Warwick Township. During our last 37 days we have seen 26 of those days with below normal temperatures here in East Nantmeal. This pattern looks to it will continue through mid-week before we finally see temperatures warming to above normal by the end of the work week. Unfortunately there is no rain in site.

Lows this morning were not too far from record cold levels for the final day of May. The lowest was the 38-degree reading at Warwick Township. During our last 37 days we have seen 26 of those days with below normal temperatures here in East Nantmeal. This pattern looks to it will continue through mid-week before we finally see temperatures warming to above normal by the end of the work week. Unfortunately there is no rain in site.

Maybe an even better example of the Urban Heat Island Problem at PHL Airport is to compare the airport to NWS COOP observations at Octoraro Lake on the SW border of Chester County at about 40 nautical miles due west of the airport. Octoraro Lake is a relative low elevation spot (260 ft asl) and that NWS COOP station is clearly seeing decreasing heat waves while PHL continues to have increasing "heat waves". The only material difference is rural vs UHI

Welp except for what you have stated before were the multiple moves from a relatively more urban locale to rural at Coatesville 1SW and of course the increase in elevation with the 1983 move to Coatesville 2W and then over to KMQS.......

Even the longest running continuous and warmest station in Chester County at Phoenixville has a clear trend toward less of the so called "heat waves"

Even the longest running and warmest station in Chester County at Phoenixville has a clear trend toward less of the so called "heat waves"

As we get into the summer months lower elevation (<450 ft asl) areas of Chester County PA will see at least one heat wave (defined as 3 or more consecutive days with highs at 90 degrees or above) while the relatively higher ridge locations (>600 ft asl) only average a heat wave every couple of years or so. Below sorted by highest to lowest elevation is a ranking of all reporting stations since 2000 with their recorded heat waves. Our lowest elevation spot at Phoenixville averages a whopping two to four times the number of heat waves as almost all other locations across the county.

As we get into the summer months lower elevation (<450 ft asl) areas of Chester County PA will see at least one heat wave (defined as 3 or more consecutive days with highs at 90 degrees or above) while the relatively higher ridge locations (>600 ft asl) only average a heat wave every couple of years or so. Below sorted by highest to lowest elevation is a ranking of all reporting stations since 2000 with their recorded heat waves. Our lowest elevation spot at Phoenixville averages a whopping two to four times the number of heat waves as almost all other locations across the county.

As we get into the summer months lower elevation (<450 ft asl) areas of Chester County PA will see at least one heat wave (defined as 3 or more consecutive days with highs at 90 degrees or above) while the relatively higher ridge locations (>600 ft asl) only average a heat wave every couple of years or so. Below sorted by highest to lowest elevation is a ranking of all reporting stations since 2000 with their recorded heat waves. Our lowest elevation spot at Phoenixville averages a whopping two to four times the number of heat waves as almost all other locations across the county.

Please do Cobalt that would be great! Thanks!!

Because it is where I live....LOL!

Inventing and mixing and matching data I see - Coatesville is not the most stable station for those 55 years....heck they only have 13 years at 1SW and 25 years at another location 2W. That only adds up to 38 years over a 55 year span. There has been no Coatesville COOP data for the last 20 years!!

Some outstanding weather on the way for much of the next week. We will stay a few degrees below normal until maybe warming up close to average temperatures for June by next weekend. In fact here in East Nantmeal May will finish as the 6th below normal month over the last 8 months dating back to last October. Rain chances look slim to none over the next week.