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Upper Flat Lake, IL Weather Forecast
Upper Flat Lake, IL Weather Forecast Date: 617 PM CDT Tue Sep 08 2026
The area/counties/county of: Greene County Il, Jersey County Il.or toggle through each period.
Tonight... Mostly clear. Not as cool with lows in the lower 70s. South winds 5 to 10 mph.
Wednesday... Mostly sunny. A slight chance of showers and thunderstorms in the morning, then a chance of showers and thunderstorms in the afternoon. Highs in the lower 90s. Southwest winds 5 to 10 mph with gusts up to 20 mph, becoming west in the afternoon. Chance of rain 40%.
Wednesday Night... Mostly cloudy with a chance of thunderstorms. A chance of showers in the evening, then showers likely after midnight. Humid with lows in the upper 60s. West winds around 5 mph. Chance of rain 70%.
Thursday... Showers and thunderstorms likely, mainly in the morning. Cooler with highs in the lower 80s. Northwest winds around 5 mph. Chance of rain 70%.
Thursday Night... Partly cloudy in the evening, then clearing. Lows around 60. Northeast winds around 5 mph.
Friday... Mostly clear. Highs in the mid 80s. Lows in the mid 60s.
Friday Night... Mostly clear. Highs in the mid 80s. Lows in the mid 60s.
Saturday... Mostly sunny with a chance of showers and thunderstorms. Highs in the upper 80s. Chance of rain 40%.
Saturday Night... Mostly cloudy with a chance of showers and thunderstorms. Lows in the mid 60s. Chance of rain 40%.
Sunday... Mostly sunny. A chance of showers and thunderstorms, mainly in the morning. Highs in the mid 80s. Chance of rain 40%.
Sunday Night... Partly cloudy with a slight chance of showers and thunderstorms. Lows in the mid 60s. Chance of rain 20%.
Monday... Mostly sunny. A chance of showers and thunderstorms, mainly in the morning. Highs in the upper 80s. Chance of rain 30%.
Monday Night... Partly cloudy. A chance of showers and thunderstorms. Lows in the mid 60s. Highs in the mid 80s. Chance of rain 40%.
POP = Probability of Precipitation
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