| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 29-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair. Patchy light fog after midnight. Low 68°. Wind northeast around 4 mph, gusting to 22 mph. |
| Thursday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain. High 88°. Heat index up to 92°. UV index up to 8. Wind east around 4 mph, gusting to 23 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain after midnight. Low 69°. Wind east around 6 mph, gusting to 21 mph, in the evening, becoming southeast after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Friday |
Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. Rain likely. Scattered thundershowers possible. High 84°. UV index up to 9. Wind southeast around 7 mph, gusting to 21 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Friday night |
Partly to mostly cloudy. Patchy light fog. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 73°. Wind south around 8 mph, gusting to 19 mph, in the evening, becoming southwest after midnight. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Saturday |
Cloudy. A chance of rain. Scattered thundershowers possible. High 80°. Wind west-northwest around 7 mph, gusting to 26 mph, in the morning, becoming north-northwest around 11 mph, gusting to 28 mph, in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Mostly cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. Low 67°. Wind north around 8 mph, gusting to 26 mph. |
| Sunday |
Partly to mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. High 84°. UV index up to 8. Wind north around 8 mph, gusting to 26 mph. |
| Sunday night |
Clear. Patchy light fog after midnight. Relatively cool. Low 64°. Wind north-northeast around 4 mph, gusting to 22 mph. |
| Monday |
Sunny. Patchy light fog in the morning. High 85°. UV index up to 8. Wind northeast around 4 mph, gusting to 23 mph. |
| Monday night |
Clear. Patchy light fog after midnight. Relatively cool. Low 64°. Wind northeast around 3 mph, gusting to 19 mph. |
| Tuesday |
Sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. High 88°. UV index up to 9. Wind southeast around 3 mph, gusting to 22 mph, in the morning, becoming 6 mph, gusting to 23 mph, in the afternoon. |
| Tuesday night |
Clear. Patchy light fog after midnight. Relatively cool. Low 67°. Wind southeast around 5 mph, gusting to 22 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.