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Hey, I pulled together the estimated PRISM grid coverage and climate data package for Chester County. PRISM is a gridded climate dataset from Oregon State University’s PRISM Climate Group. Instead of only using individual weather stations, PRISM takes station observations, terrain, elevation, coastal effects, and other geographic factors into account to estimate climate variables across a continuous grid. It is commonly used for precipitation, temperature, dew point, vapor pressure deficit, solar/climate analysis, drought work, agricultural analysis, hydrology, and local climate comparisons. For Chester County, I estimated the county intersects about 151 PRISM-style 4 km grid cells. Each 4 km grid cell is: 4,000 meters wide by 4,000 meters tall About 2.49 miles wide by 2.49 miles tall 16 square kilometers About 6.18 square miles The coordinate file I made gives the estimated centerpoint of each 4 km cell covering at least part of Chester County. The file is latitude, longitude format with no header row, so it should be easy to paste into mapping tools, GIS software, or scripts. The ZIP file size is about 58 MB. Unzipped, the data is about 208 MB. What is included in the data package: Daily PRISM files from 1981 through July 1, 2026 Monthly PRISM files from 1895 through May 2026 1991–2020 monthly normals 1991–2020 daily normals The daily files are the day-by-day weather/climate estimates for each Chester County grid cell. These are useful for looking at specific storms, heat waves, cold snaps, wet/dry stretches, day-to-day variability, growing season conditions, and longer-term local trends. The monthly files go much farther back, starting in 1895 and running through May 2026. These are better for long-term climate history because they cover more than 130 years. They are useful for comparing recent months to the historical record, ranking wet/dry months, looking at long-term warming trends, and comparing different decades. The 1991–2020 monthly normals are the modern 30-year baseline averages. These tell you what is “normal” for each month at each grid cell, using the current standard climate-normal period. The 1991–2020 daily normals are the day-of-year baseline values. These are useful when you want to compare a specific date, like July 1 or October 15, against what is normally expected for that time of year. The main variables included or represented are: ppt: precipitation tmin: minimum temperature tmean: mean temperature tmax: maximum temperature tdmean: mean dew point temperature vpdmin: minimum vapor pressure deficit vpdmax: maximum vapor pressure deficit Depending on the specific PRISM product set, solar-related variables may also be available: solclear: clear-sky solar radiation soltotal: total solar radiation on a horizontal surface solslope: solar radiation adjusted for slope/aspect soltrans: cloud transmittance The temperature variables are useful for heat, cold, frost, growing season, and general climate work. The precipitation variable is useful for rainfall/snow-water equivalent, storm totals, drought, wet spells, and long-term precipitation trends. Dew point is useful because it describes actual atmospheric moisture better than relative humidity alone. It helps show humid-air events, muggy periods, and moisture transport. Vapor pressure deficit, or VPD, is useful for plant stress, evaporation demand, drought stress, and agricultural or ecological analysis. Higher VPD generally means the atmosphere is pulling moisture more aggressively from plants and surfaces. There is also a finer 800 meter PRISM grid option. The relationship is simple: one 4 km cell can be divided into 25 smaller 800 m cells, because 4,000 meters divided by 800 meters is 5 cells across, and 5 by 5 equals 25. So one 4 km cell equals: 5 smaller 800 m cells across 5 smaller 800 m cells tall 25 total 800 m cells inside one 4 km cell Each 800 m grid cell is: 800 meters wide by 800 meters tall About 0.50 miles wide by 0.50 miles tall 0.64 square kilometers About 0.247 square miles For Chester County, the rough 800 m estimate is around 3,300 cells if counting cells that touch the county boundary. If you simply subdivided all 151 estimated 4 km cells into 25 smaller cells each, that would be 3,775 possible 800 m subcells, but the more realistic county-clipped estimate is closer to 3,300 because the county boundary cuts through edge cells. The 800 m version would give much more local detail, especially in areas where terrain, elevation, urbanization, valleys, or county-edge effects matter. It would also be much larger. Since 800 m resolution has 25 times as many grid cells as 4 km resolution, the same date range and variables could be up to roughly 25 times larger. As a rough estimate, if the 4 km package is 58 MB zipped and 208 MB unzipped, the equivalent 800 m package could be somewhere around: 1.45 GB zipped 5.2 GB unzipped That is only a rough scaling estimate, because compression varies by variable and file structure, but it gives the right ballpark. I started with the 4 km version because it is much smaller, easier to transfer, and still gives a good countywide climate picture. If you want the higher-detail 800 m version, I can pull/build that too. Link to 4km https://drive.google.com/file/d/1uD5Q3O_voxpLItJHbWMpdAkgKtBMc-k0/view?usp=drivesdk Sent from my SM-S731U using Tapatalk

It was super hot in Pottstown, PA, yesterday, but the Big Boy didn’t disappoint.

My weather station is showing 98.6 with a dewpoint of 83.8 for a feels like of 128....I think my station has heat stroke. It's bad out there, but not that bad.

96/77 (112 HI) at home. 84/76 (95 HI) at DCL.

98/76/112 Beach isnt that bad..slight sea breeze probably mid 80s Hot sand

Refreshed…it’s all the sites mesowest has. ASOS includes the 5 min data. https://www.weather.gov/wrh/hazards?&zoom=9&scroll_zoom=false&center=43.329173667843904,-71.68579101562501&boundaries=false,false,false,false,false,false,false,false,false,false,false,false,false&tab=observation&obs=true&obs_type=air_temp&obs_popup=false&obs_density=10&obs_provider=ALL

Yeah, I'm a bit surprised that IAD has been running 2-3 degrees cooler than surrounding obs.

98/77/113 HI good lord

Thanks for this page. Is this hourly obs or if it is refreshed is it also ASOS stations that upload near real time?

Well aren't you the beaerer of good news lol. No matter what, its still going to be hot next week with temps in the mid to upper 90s here.

96 here I have my AC full blast and I dont feel it. They must have lowered the electricity.

Marginal risk issued for tn river and middle tn parts of east tn also in north al and ga north east Ms as well points northward in a pretty big spaced out marginal slight also enhanced risk in the north or central plains .

My wife is in the city and just walking twen blocks, she was soaked with sweat. ITs pretty gross as I Can recall living up there and summers were brutal. No relief whatsoever. For her to compain about the heat as she loves it, you knows its bad lol

My guess is that the EURO’s July update on Sunday is also off the charts @Stormchaserchuck1 The equatorial subsurface in the EPAC is ridiculous

97/72 w/ NW wind here on the south shore of LI Making up for all those days with a sea breeze. Probably will fall just short of 100 here before the sea breeze comes through

Running just behind yesterday’s pace now at WXW1. 91.7°

94/71

It'll be criminal for IAD to not hit 100° if BWI and DCA do.

97 in Ashburn

True but I'll take the florida climo over the dry death ridge

Several mesonet site creeping into the upper 90s my money is on Goldsboro and Federalsburg going gangbusters on the eastern shore.

93° with a heat index of 110° according to my tempest. Today feels like the day I finally crack 100°...hit 99.9° a bunch yesterday but never got over the hump. Also just saw that Leesburg canceled the 4th of July parade tomorrow because of the heat. We go every year, so it's a real bummer, but I get it.

94/70. Crazy how a 70 degree dew point can feel so dry.

you’re concerned about fireworks smoke? lololol