| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 08-Jun-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Partly to mostly cloudy in the morning, becoming cloudy in the afternoon. Rain likely. Scattered thunderstorms likely. High 86°. Heat index up to 93°. UV index up to 5. Wind south-southwest around 7 mph, gusting to 26 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Tonight |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Warm. Low 76°. Wind south around 5 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Tuesday |
Partly to mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. Hot. High 93°. Heat index up to 104°. UV index up to 10. Wind southwest around 9 mph, gusting to 27 mph. |
| Tuesday night |
Clear in the evening, becoming mostly clear after midnight. Moderate fog after midnight. Low 75°. Wind southwest around 6 mph, gusting to 24 mph. |
| Wednesday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Very hot. High 94°. Heat index up to 104°. UV index up to 9. Wind south-southwest around 9 mph, gusting to 28 mph. |
| Wednesday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Warm. Low 76°. Wind south-southwest around 7 mph, gusting to 24 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Thursday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 95°. Heat index up to 106°. UV index up to 10. Wind south-southwest around 8 mph, gusting to 27 mph, in the morning, becoming 12 mph, gusting to 29 mph, in the afternoon. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. Rain likely. Scattered thunderstorms likely. Low 72°. Wind west-southwest around 7 mph, gusting to 25 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Friday |
Partly cloudy. Patchy light fog in the morning. Hot. High 88°. Heat index up to 92°. UV index up to 7. Wind west-northwest around 6 mph, gusting to 25 mph. |
| Friday night |
Partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Low 67°. Wind west-southwest around 2 mph, gusting to 21 mph, in the evening, becoming south-southwest after midnight. |
| Saturday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 89°. Heat index up to 95°. UV index up to 9. Wind south-southwest around 6 mph, gusting to 24 mph. |
| Saturday night |
Mostly cloudy in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 67°. Wind north-northeast around 6 mph, gusting to 20 mph. |
| Sunday |
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. High 83°. UV index up to 7. Wind east-northeast around 6 mph, gusting to 24 mph. |
| Sunday night |
Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Low 68°. Wind east around 7 mph, gusting to 23 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.