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Ottawa, IL Weather Forecast
Ottawa, IL Weather Forecast Date: 841 PM CDT Wed Sep 09 2026
The area/counties/county of: La Salle, including the cities of: Ottawa, Streator, La Salle, Mendota, and Marseilles.or toggle through each period.
Tonight... Partly cloudy in the evening, then becoming mostly cloudy. Patchy fog after midnight. Lows in the mid 60s. Southwest winds around 5 mph, becoming northwest after midnight.
Thursday... Mostly cloudy. Patchy fog early in the morning. A slight chance of showers in the morning. Highs in the upper 70s. North winds around 5 mph. Chance of precipitation 20%.
Thursday Night... Clear. Lows in the lower 50s. Light and variable winds.
Friday... Sunny. Highs around 80. Southeast winds 5 to 10 mph.
Friday Night... Mostly clear in the evening, then becoming partly cloudy. Lows in the lower 60s. Southeast winds around 5 mph.
Saturday... Partly cloudy. Highs in the mid 80s.
Saturday Night... A slight chance of thunderstorms in the evening. Partly cloudy with a slight chance of showers. Lows in the lower 60s. Chance of precipitation 20%.
Sunday... Partly cloudy with a slight chance of showers in the morning, then mostly cloudy in the afternoon. Highs in the lower 80s. Chance of precipitation 20%.
Sunday Night... Mostly cloudy. Lows in the mid 60s.
Monday... Partly cloudy with a chance of showers. Highs in the upper 80s. Chance of precipitation 40%.
Monday Night... Mostly clear in the evening, then becoming partly cloudy. A chance of showers. Lows in the upper 60s. Chance of precipitation 50%.
Tuesday... Mostly cloudy. A chance of showers in the afternoon. Highs in the lower 80s. Chance of precipitation 30%.
Tuesday Night... Mostly cloudy. A chance of showers after midnight. Lows in the lower 60s. Chance of precipitation 40%.
POP = Probability of Precipitation
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