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St Clair County, IL Weather Forecast
St Clair County, IL Weather Forecast Date: 127 AM CDT Mon Sep 14 2026
The area/counties/county of: Madison County Il, including the cities of: Alton, Edwardsville, Belleville, Cahokia, Saint Charles, and Saint Louis.or toggle through each period.
Rest of Tonight... Mostly cloudy. Near steady temperature in the mid 60s. Northeast winds 5 to 10 mph with gusts up to 20 mph.
Monday... Mostly sunny. Highs in the upper 80s. East winds 10 to 15 mph.
Monday Night... Mostly clear. Lows in the lower 70s. Southeast winds 10 to 15 mph.
Tuesday... Sunny. A chance of showers and thunderstorms in the afternoon. Hot with highs in the upper 90s. South winds 5 to 10 mph. Chance of rain 50%. Heat index values up to 108.
Tuesday Night... Partly cloudy with a chance of showers. A chance of thunderstorms, mainly in the evening. Humid with lows in the lower 70s. South winds around 5 mph in the evening, becoming light and variable. Chance of rain 50%. Heat index values up to 103 early in the evening.
Wednesday... Mostly sunny with a slight chance of showers. A slight chance of thunderstorms in the afternoon. Hot with highs in the mid 90s. Chance of rain 20%. Heat index values up to 105.
Wednesday Night... Mostly clear. Hot. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105.
Thursday... Mostly clear. Hot. Lows in the mid 70s. Highs in the mid 90s. Heat index values up to 105.
Thursday Night... Partly cloudy. Lows in the lower 70s. Highs in the lower 90s. Heat index values up to 100.
Friday... Partly cloudy. Lows in the lower 70s. Highs in the lower 90s. Heat index values up to 100.
Saturday... Partly cloudy. Lows in the lower 70s. Highs in the lower 90s. Heat index values up to 100.
Saturday Night... Partly cloudy. A slight chance of showers and thunderstorms after midnight. Lows in the upper 60s. Chance of rain 20%.
POP = Probability of Precipitation
St Clair County Radar Loop
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