CHESTER COUNTY, PA — September is proving it still has a little summer left in the tank, with a warm start to the week, a few midweek showers, and a rebound into sunny skies as we head toward the weekend. Here’s your full look at what to expect in Chester County for the week beginning Sunday, September 14, 2025.
Sunday: A Golden Start
Today brings plenty of sunshine and a high near 84°F. Winds stay calm, shifting north at just 5 mph, making it an ideal day for anything outdoors — from backyard barbecues to catching up on yard work. Tonight cools down nicely to 59°F under mostly clear skies.
Monday: Morning Fog, Then Sun
Early risers may notice patchy fog before 7 a.m., but it burns off quickly. Expect a mostly sunny day with highs around 82°F. Winds are calm, turning light northeast at 5 mph. Monday night clouds move in, with lows near 57°F.
Tuesday & Wednesday: Clouds and Showers Sneak In
Tuesday starts partly sunny with highs near 77°F. A slight chance of afternoon showers (20%) increases after dark, with lows around 58°F and rain chances climbing to 40% overnight.
Wednesday keeps things unsettled. Expect mostly cloudy skies, highs near 74°F, and a 50% chance of showers through the day. Nighttime remains damp, with lows around 60°F and a 40% chance of lingering showers.
Thursday: Clearing Out
Thursday begins with a 30% chance of morning showers, but skies turn partly sunny later, with highs rebounding to 78°F. By night, the clouds break and we dip to a pleasant 59°F.
Friday & Saturday: Back to Summer Mode
Friday looks like the week’s weather jackpot — sunny skies and a high near 85°F. Friday night stays mostly clear with lows near 60°F. Saturday cools slightly but keeps the sunshine, with highs near 77°F — perfect for weekend plans.
The Takeaway
Chester County gets a little bit of everything this week: warm sunshine today and Monday, midweek showers Tuesday and Wednesday, and a picture-perfect warmup just in time for Friday and Saturday. With highs mostly in the 70s to mid-80s, it’s a comfortable stretch that bridges summer’s end and fall’s arrival.
☀️ Stay ahead of shifting skies and weekend sunshine — follow the MyChesCo Weather Center for live updates, radar, and everything you need to plan your week with confidence.
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