| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Saturday, 23-May-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Low 64°. Wind west around 3 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Partly to mostly cloudy in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. A chance of rain. Scattered thundershowers possible. High 80°. UV index up to 8. Wind north-northwest around 4 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Clear. Light to moderate fog after midnight. Low 59°. Wind northeast around 2 mph, gusting to 19 mph. |
| Monday |
Sunny in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. High 80°. UV index up to 7. Wind east around 4 mph, gusting to 22 mph. |
| Monday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. Low 62°. Wind east around 3 mph, gusting to 17 mph. |
| Tuesday |
Mostly cloudy to cloudy in the morning, becoming dense overcast in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then rain likely in the afternoon. Scattered thunderstorms likely. High 71°. Wind east around 5 mph, gusting to 17 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch. |
| Tuesday night |
Cloudy in the evening, becoming dense overcast after midnight. Light to moderate fog. Rain likely in the evening, then a chance of rain after midnight. Thunderstorms very likely, some possibly severe. Low 66°. Wind east-southeast around 5 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch. |
| Wednesday |
Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. Rain likely. Thunderstorms very likely, some possibly severe. High 80°. UV index up to 7. Wind south-southeast around 5 mph, gusting to 21 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch. |
| Wednesday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Moderate fog. Rain likely in the evening, then a chance of rain after midnight. Scattered thunderstorms likely. Low 67°. Wind east-southeast around 4 mph, gusting to 20 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday |
Cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Light to moderate fog. Rain likely. Scattered thunderstorms likely. High 73°. Wind east-southeast around 5 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch. |
| Thursday night |
Mostly cloudy to cloudy. Light to moderate fog. Rain likely in the evening, then a chance of rain after midnight. Scattered thunderstorms likely. Low 67°. Wind east-southeast around 5 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch. |
| Friday |
Mostly cloudy to cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. High 76°. UV index up to 9. Wind east-northeast around 8 mph, gusting to 29 mph, in the morning, becoming 12 mph, gusting to 29 mph, in the afternoon. |
| Friday night |
Partly cloudy in the evening, becoming clear after midnight. Relatively cool. Low 56°. Wind northeast around 7 mph, gusting to 26 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.