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Flat Lake, IL Weather Forecast
Flat Lake, IL Weather Forecast Date: 508 AM CDT Sat Sep 26 2026
The area/counties/county of: Greene County Il, Jersey County Il.or toggle through each period.
Today... Mostly cloudy. A chance of sprinkles this morning, then a slight chance of showers this afternoon. Highs in the lower 70s. East winds around 5 mph. Chance of rain 20%.
Tonight... Mostly cloudy. A slight chance of showers after midnight. Lows in the upper 50s. East winds around 5 mph in the evening, becoming light and variable. Chance of rain 20%.
Sunday... Mostly sunny. Highs in the mid 70s. East winds around 5 mph.
Sunday Night... Mostly clear in the evening, then becoming partly cloudy. Lows in the mid 50s. Northeast winds around 5 mph.
Monday... Mostly sunny. Highs in the upper 70s. East winds around 5 mph.
Monday Night... Mostly clear. Lows in the mid 50s.
Tuesday... Mostly sunny. Highs in the lower 80s.
Tuesday Night... Mostly cloudy. A slight chance of showers in the evening, then a chance of showers with a slight chance of thunderstorms after midnight. Lows in the mid 60s. Chance of rain 50%.
Wednesday... A slight chance of thunderstorms. Showers likely. Highs in the upper 70s. Chance of rain 70%.
Wednesday Night... Showers likely with a slight chance of thunderstorms. Lows in the mid 60s. Highs in the upper 70s. Chance of rain 60%.
Thursday... Showers likely with a slight chance of thunderstorms. Lows in the mid 60s. Highs in the upper 70s. Chance of rain 60%.
Thursday Night... Mostly cloudy with a 50% chance of showers. Lows in the lower 60s.
POP = Probability of Precipitation
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