| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Thursday, 30-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Precipitation showery or intermittent. Low 70°. Wind east-southeast around 5 mph, gusting to 21 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Friday |
Dense overcast in the morning, becoming mostly cloudy to 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 84°. UV index up to 6. Wind south-southeast around 6 mph, gusting to 16 mph, in the morning, becoming 9 mph, gusting to 23 mph, in the afternoon. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch. |
| Friday night |
Mostly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog. Rain likely. Scattered thunderstorms likely. Low 73°. Wind south-southeast around 8 mph, gusting to 22 mph, in the evening, becoming southwest after midnight. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Saturday |
Mostly cloudy to cloudy in the morning, becoming cloudy in the afternoon. Patchy light fog in the morning. Rain likely. Scattered thunderstorms likely. High 79°. Wind west around 10 mph, gusting to 27 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch. |
| Saturday night |
Dense overcast in the evening, becoming cloudy after midnight. Patchy light fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Breezy. Low 69°. Wind north-northwest around 11 mph, gusting to 26 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Sunday |
Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. High 80°. UV index up to 5. Wind north-northwest around 11 mph, gusting to 27 mph. |
| Sunday night |
Fair in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Relatively cool. Low 64°. Wind north-northwest around 4 mph, gusting to 23 mph. |
| Monday |
Sunny. Light to moderate fog in the morning. High 84°. UV index up to 9. Wind north around 4 mph, gusting to 22 mph. |
| Monday night |
Clear. Patchy light fog after midnight. Relatively cool. Low 64°. Wind east-northeast around 3 mph, gusting to 18 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. High 86°. UV index up to 9. Wind east around 3 mph, gusting to 20 mph. |
| Tuesday night |
Clear in the evening, becoming fair after midnight. Patchy light fog after midnight. Relatively cool. Low 65°. Wind east around 3 mph, gusting to 18 mph. |
| Wednesday |
Sunny in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. High 87°. UV index up to 6. Wind southeast around 2 mph, gusting to 21 mph, in the morning, becoming northeast in the afternoon. |
| Wednesday night |
Mostly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 69°. Wind east around 2 mph, gusting to 17 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.