Weather WorldJefferson County, IL 7-Day Night Weather Forecast
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Jefferson County, IL Weather Forecast
Jefferson County, IL Weather Forecast Date: 507 PM CDT Sun Oct 04 2026
The area/counties/county of: Jefferson, including the city of Mount Vernon.or toggle through each period.
Tonight... Clear. Lows in the lower 50s. North winds around 5 mph.
Monday... Sunny. Highs in the upper 70s. Northeast winds 5 to 10 mph.
Monday Night... Clear. Lows in the mid 40s. Northeast winds around 5 mph.
Tuesday... Sunny. Highs in the upper 70s. Southeast winds around 5 mph.
Tuesday Night... Clear. Lows around 50. Calm winds, becoming southwest around 5 mph after midnight.
Wednesday... Clear. Highs in the mid 80s. Lows in the mid 50s.
Thursday... Clear. Highs in the mid 80s. Lows in the mid 50s.
Friday... Mostly clear. Highs in the mid 80s. Lows in the mid 50s.
Friday Night... Mostly clear. Highs in the mid 80s. Lows in the mid 50s.
Saturday... Partly cloudy. Highs in the lower 80s. Lows in the upper 50s.
Saturday Night... Partly cloudy. Highs in the lower 80s. Lows in the upper 50s.
POP = Probability of Precipitation
Jefferson County Radar Loop
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