| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 01-Jun-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair. Low 69°. Wind northeast around 4 mph, gusting to 24 mph. |
| Tuesday |
Mostly sunny. High 83°. UV index up to 8. Wind east-northeast around 6 mph, gusting to 27 mph, in the morning, becoming 10 mph, gusting to 27 mph, in the afternoon. |
| Tuesday night |
Clear. Low 61°. Wind east-northeast around 5 mph, gusting to 25 mph. |
| Wednesday |
Partly to mostly sunny in the morning, becoming sunny in the afternoon. High 83°. UV index up to 9. Wind east around 5 mph, gusting to 25 mph. |
| Wednesday night |
Clear in the evening, becoming fair after midnight. Relatively cool. Low 60°. Wind east-southeast around 4 mph, gusting to 23 mph, in the evening, becoming south after midnight. |
| Thursday |
Partly cloudy. Hot. High 86°. UV index up to 7. Wind south around 6 mph, gusting to 25 mph. |
| Thursday night |
Fair in the evening, becoming partly cloudy after midnight. Low 62°. Wind south around 6 mph, gusting to 21 mph. |
| Friday |
Partly cloudy in the morning, becoming mostly cloudy in the afternoon. A slight chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 87°. UV index up to 7. Wind south around 7 mph, gusting to 26 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Mostly cloudy to cloudy. Light to moderate fog after midnight. A slight chance of rain in the evening, then rain likely after midnight. Precipitation showery or intermittent. Low 65°. Wind south around 6 mph, gusting to 17 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Saturday |
Mostly cloudy to cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. High 85°. UV index up to 10. Wind south-southwest around 8 mph, gusting to 24 mph. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch. |
| Saturday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Moderate fog. Rain likely. Scattered thundershowers possible. Low 69°. Wind south around 5 mph, gusting to 17 mph. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch. |
| Sunday |
Mostly cloudy in the morning, becoming cloudy in the afternoon. Moderate fog in the morning. A chance of rain. Thunderstorms very likely, some possibly severe. High 81°. UV index up to 5. Wind west-southwest around 5 mph, gusting to 16 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog. A chance of rain in the evening, then a slight chance of rain after midnight. Thunderstorms very likely, some possibly severe. Low 71°. Wind south-southeast around 3 mph in the evening, becoming southwest after midnight. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.