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Altamont Reservoir, IL Weather Forecast
Altamont Reservoir, IL Weather Forecast Date: 637 AM CDT Mon Aug 10 2026
The area/counties/county of: Effingham, including the city of Effingham.or toggle through each period.
Today... Mostly sunny. Highs in the lower 90s. Southwest winds 5 to 10 mph with gusts up to 20 mph. Heat index values up to 105 this afternoon.
Tonight... Partly cloudy in the evening, then mostly cloudy with a slight chance of showers and thunderstorms after midnight. Humid with lows in the mid 70s. South winds 5 to 10 mph. Chance of rain 20%.
Tuesday... Mostly sunny. A slight chance of showers and thunderstorms in the morning. Humid with highs in the lower 90s. Southwest winds around 10 mph with gusts up to 20 mph. Chance of rain 20%. Heat index values up to 106 in the afternoon.
Tuesday Night... Partly cloudy. Humid with lows in the mid 70s. Southwest winds 5 to 10 mph.
Wednesday... Mostly sunny with a chance of showers. A chance of thunderstorms in the afternoon. Humid with highs around 90. Southwest winds 5 to 10 mph. Chance of rain 50%. Heat index values up to 103.
Wednesday Night... Partly cloudy in the evening, then becoming mostly cloudy. A chance of thunderstorms in the evening. A chance of showers. Lows in the lower 70s. Chance of rain 50%.
Thursday... A chance of thunderstorms. Showers likely, mainly in the morning. Highs in the mid 80s. Chance of rain 60%.
Thursday Night... A chance of thunderstorms in the evening. Showers likely. Lows in the upper 60s. Chance of rain 70%.
Friday... A chance of showers in the morning. Partly sunny. Highs in the mid 80s. Chance of rain 40%.
Friday Night... Partly cloudy. A chance of showers after midnight. Lows in the upper 60s. Chance of rain 30%.
Saturday... Partly cloudy. Highs in the mid 80s. Lows in the lower 70s.
Saturday Night... Partly cloudy. Highs in the mid 80s. Lows in the lower 70s.
POP = Probability of Precipitation
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