| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Friday, 12-Jun-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Sunny. Hot. High 88°. UV index up to 10. Wind west around 3 mph, gusting to 24 mph. |
| Tonight |
Mostly clear in the evening, becoming partly cloudy after midnight. Low 64°. Wind south-southeast around 3 mph, gusting to 18 mph. |
| Saturday |
Mostly cloudy. A chance of rain in the morning, then a slight chance of rain in the afternoon. Thunderstorms very likely, some severe. High 86°. UV index up to 5. Wind south around 7 mph, gusting to 24 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Saturday night |
Mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Thunderstorms very likely, some possibly severe. Low 68°. Wind south-southwest around 6 mph, gusting to 21 mph, in the evening, becoming west after midnight. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Sunday |
Mostly cloudy in the morning, becoming mostly sunny in the afternoon. A chance of rain. Scattered thundershowers possible. Breezy. High 78°. UV index up to 9. Wind north-northwest around 11 mph, gusting to 29 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Partly cloudy. Relatively cool. Low 61°. Wind north-northwest around 7 mph, gusting to 26 mph, in the evening, becoming 3 mph, gusting to 17 mph, after midnight. |
| Monday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. High 80°. UV index up to 7. Wind west around 5 mph, gusting to 23 mph. |
| Monday night |
Partly cloudy in the evening, becoming fair after midnight. Relatively cool. Low 59°. Wind west around 5 mph, gusting to 22 mph. |
| Tuesday |
Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. High 82°. UV index up to 6. Wind southwest around 9 mph, gusting to 28 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Partly cloudy. Patchy light fog after midnight. A chance of rain. Scattered thunderstorms likely. Low 65°. Wind southwest around 6 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday |
Partly to mostly sunny. Patchy light fog in the morning. Hot. High 91°. Heat index up to 94°. UV index up to 9. Wind south around 9 mph, gusting to 28 mph. |
| Wednesday night |
Fair to partly cloudy in the evening, becoming mostly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Thunderstorms very likely, some severe. Breezy. Low 70°. Wind southwest around 15 mph, gusting to 27 mph, in the evening, becoming 10 mph, gusting to 19 mph, after midnight. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday |
Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain. High 84°. UV index up to 7. Wind west-northwest around 6 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 66°. Wind northeast around 2 mph, gusting to 22 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.