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City of Waterloo, IllinoisWaterloo, IL 7-Day Night Weather Forecast
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Waterloo, IL Weather Forecast
Waterloo, IL Weather Forecast Date: 858 PM CDT Thu Sep 03 2026
The area/counties/county of: Monroe County Il, Jefferson County Mo.or toggle through each period.
Tonight... Mostly clear. Lows in the mid 70s. South winds around 5 mph. Heat index values up to 103 early this evening.
Friday... Sunny, hot with highs in the upper 90s. Southwest winds around 5 mph. Heat index values up to 107.
Friday Night... Mostly clear. Lows in the mid 70s. Southwest winds around 5 mph. Heat index values up to 104 early in the evening.
Saturday... Sunny, hot with highs in the upper 90s. West winds around 5 mph. Heat index values up to 110.
Saturday Night... Mostly clear. Lows in the lower 70s. Northwest winds around 5 mph in the evening, becoming light and variable. Heat index values up to 104 early in the evening.
Sunday... Mostly clear. Hot. Highs in the mid 90s. Lows in the upper 60s. Heat index values up to 105.
Monday... Mostly clear. Hot. Highs in the mid 90s. Lows in the upper 60s. Heat index values up to 105.
Tuesday... Mostly clear. Hot. Highs in the mid 90s. Lows in the upper 60s. Heat index values up to 105.
Tuesday Night... Mostly clear. Hot. Lows in the mid 70s. Highs in the upper 90s. Heat index values up to 105.
Wednesday... Mostly clear. Hot. Lows in the mid 70s. Highs in the upper 90s. Heat index values up to 105.
Wednesday Night... Mostly clear. A slight chance of showers and thunderstorms after midnight. Lows in the mid 70s. Chance of rain 20%. Heat index values up to 100 early in the evening.
POP = Probability of Precipitation
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