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Cortland, IL 7-Day Night Weather Forecast
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Cortland, IL Weather Forecast
Cortland, IL Weather Forecast Date: 836 PM CDT Mon Sep 14 2026
The area/counties/county of: De Kalb, including the cities of: Dekalb and Sycamore.or toggle through each period.
Tonight... Mostly cloudy. A slight chance of showers and thunderstorms in the evening. Showers and a chance of thunderstorms after midnight. Not as cool. Near steady temperature in the mid 60s. South winds 15 to 20 mph with gusts up to 25 mph. Chance of precipitation 80%.
Tuesday... Mostly cloudy. Showers early in the morning. A chance of thunderstorms. A chance of showers in the late morning and afternoon. More humid with highs in the upper 70s. Southwest winds 10 to 15 mph, becoming west 5 to 10 mph in the afternoon. Chance of precipitation 90%.
Tuesday Night... Mostly cloudy. A chance of showers and thunderstorms early in the evening, then a slight chance of showers and thunderstorms in the late evening and early morning. A chance of showers and thunderstorms late. Lows around 60. Northwest winds 5 to 10 mph, becoming northeast after midnight. Chance of precipitation 50%.
Wednesday... Mostly cloudy. Showers likely in the morning. A chance of thunderstorms. A chance of showers in the afternoon. Highs in the lower 70s. East winds 5 to 10 mph. Chance of precipitation 60%.
Wednesday Night... Mostly cloudy. A slight chance of showers and thunderstorms in the evening, then showers likely with a chance of thunderstorms after midnight. Near steady temperature in the mid 60s. East winds around 5 mph. Chance of precipitation 60%.
Thursday... Mostly cloudy. Showers likely with a chance of thunderstorms in the morning. Highs in the upper 70s. Chance of precipitation 60%.
Thursday Night... Mostly cloudy. A slight chance of showers in the evening, then a chance of showers after midnight. Lows in the mid 60s. Chance of precipitation 30%.
Friday... Mostly cloudy with a 40% chance of showers. Highs in the lower 80s.
Friday Night... Partly cloudy with a chance of showers. Lows in the upper 60s. Chance of precipitation 40%.
Saturday... Partly cloudy with a chance of showers. Highs in the lower 80s. Chance of precipitation 50%.
Saturday Night... Partly cloudy in the evening, then becoming mostly cloudy. A chance of showers. Lows in the mid 60s. Chance of precipitation 50%.
Sunday... Mostly cloudy with a chance of showers. Highs in the upper 70s. Chance of precipitation 40%.
Sunday Night... Mostly cloudy with a chance of showers. Lows in the upper 50s. Chance of precipitation 40%.
POP = Probability of Precipitation
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