CHESTER COUNTY, PA — Summer isn’t going quietly. Chester County kicks off this week with one last blast of heat before storms roll in and temperatures cool down to more comfortable levels. From sweltering sunshine to breezy, cloud-covered afternoons, this forecast is anything but boring. Here’s what you can expect as we move through the week of Sunday, August 17, 2025.
Sunday: Hot and Sunny
Today will be classic mid-August — sunny skies and a high near 91°F. A light southwest breeze around 5 mph won’t do much to ease the heat, so hydrate and take it slow if you’re outdoors. Tonight, a 40% chance of showers and thunderstorms creeps in, especially before 4 a.m. Rainfall could be a quarter to half an inch in spots. Overnight lows dip to 67°F, with winds shifting north at 5 to 10 mph after midnight.
Monday & Tuesday: Clouds, Showers, and a Chill-Down
Monday brings a big change. Highs drop to around 74°F under mostly cloudy skies, with scattered showers and storms possible throughout the afternoon and evening. Winds pick up from the northeast at 10 mph, gusting up to 20 mph, so it’ll feel a bit breezy. Overnight lows settle at 62°F.
Tuesday stays on the cooler side, with a high near 74°F and another round of clouds and scattered showers. Rain chances are about 30%, mainly in the afternoon and evening. Lows remain mild at 63°F.
Wednesday & Thursday: Pop-Up Showers, Slightly Warmer
Wednesday will be partly sunny, with a high near 79°F. Showers are possible in the morning and again after 2 p.m. (40% chance). By nightfall, skies remain mostly cloudy with a low near 62°F.
Thursday is a touch warmer at 81°F with mostly sunny skies, but a 30% chance of showers lingers in the afternoon. By evening, skies clear out with lows steady near 62°F.
Friday & Saturday: Summer’s Sweet Spot
Friday and Saturday deliver the kind of weather August dreams are made of. Mostly sunny skies, highs in the low 80s (83°F Friday, 82°F Saturday), and comfortable lows near 62°F at night. No storms, no extreme heat — just pleasant, golden-summer days to wrap up the week.
The Takeaway
This week is a weather rollercoaster: from 91°F heat today to a refreshing stretch in the mid-70s Monday and Tuesday, before bouncing back to a comfortable low-80s groove by the weekend. Keep the umbrella handy for scattered storms midweek, but by Friday, it’s smooth sailing.
☀️ Want to stay ahead of the storms and soak up the sunshine? Visit the MyChesCo Weather Center for live updates, local radar, and your day-to-day forecast.
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