| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 03-Aug-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. A slight chance of rain. High 85°. UV index up to 8. Wind northeast around 2 mph, gusting to 21 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Tonight |
Fair. Relatively cool. Low 64°. Wind east around 3 mph in the evening, becoming south-southeast after midnight. |
| Tuesday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. High 89°. UV index up to 8. Wind south-southeast around 4 mph, gusting to 22 mph. |
| Tuesday night |
Partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. A slight chance of rain. Low 68°. Wind south-southeast around 5 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 92°. Heat index up to 98°. UV index up to 8. Wind south-southeast around 5 mph, gusting to 22 mph. |
| Wednesday night |
Partly cloudy. Moderate fog after midnight. A slight chance of rain in the evening, then rain likely after midnight. Precipitation showery or intermittent. Low 70°. Wind east around 4 mph, gusting to 17 mph, in the evening, becoming southeast after midnight. Chance of precipitation 70 percent. Precipitation mostly between half an inch and one inch. |
| Thursday |
Mostly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Light to moderate fog in the morning. Rain likely. Scattered thundershowers possible. High 85°. UV index up to 5. Wind southwest around 4 mph, gusting to 19 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog. A chance of rain in the evening, then a slight chance of rain after midnight. Low 73°. Wind south-southwest near calm. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Friday |
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 86°. Heat index up to 92°. UV index up to 5. Wind northwest around 2 mph, gusting to 17 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Low 71°. Wind northeast around 2 mph, gusting to 17 mph, in the evening, becoming south-southwest after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 91°. Heat index up to 98°. UV index up to 8. Wind southwest around 2 mph, gusting to 19 mph. |
| Saturday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. Low 73°. Wind south around 8 mph, gusting to 21 mph. |
| Sunday |
Sunny in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 95°. Heat index up to 103°. UV index up to 9. Wind southwest around 9 mph, gusting to 21 mph. |
| Sunday night |
Mostly clear in the evening, becoming fair after midnight. Low 73°. Wind west-southwest around 6 mph. |
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