| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 22-Apr-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair to partly cloudy in the evening, becoming fair after midnight. Moderate fog after midnight. Low 57°. Wind south-southwest around 5 mph, gusting to 22 mph. |
| Thursday |
Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Warm. High 80°. UV index up to 7. Wind south around 8 mph, gusting to 25 mph, in the morning, becoming 12 mph, gusting to 29 mph, in the afternoon. |
| Thursday night |
Partly cloudy in the evening, becoming cloudy after midnight. Patchy light fog after midnight. Rain likely after midnight. Thunderstorms very likely, some possibly severe. Low 59°. Wind south around 12 mph, gusting to 25 mph, in the evening, becoming 8 mph, gusting to 17 mph, after midnight. Chance of precipitation 80 percent. Precipitation mostly between a quarter and half an inch. |
| Friday |
Cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely in the morning, then a slight chance of rain in the afternoon. Scattered thunderstorms likely. High 73°. UV index up to 6. Wind west-southwest around 6 mph, gusting to 23 mph. Chance of precipitation 70 percent. Precipitation mostly around half an inch. |
| Friday night |
Clear. Patchy light fog after midnight. Low 52°. Wind north-northwest around 4 mph, gusting to 21 mph. |
| Saturday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 74°. UV index up to 6. Wind northeast around 5 mph, gusting to 23 mph. |
| Saturday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 51°. Wind northeast around 6 mph, gusting to 18 mph. |
| Sunday |
Partly cloudy in the morning, becoming mostly cloudy in the afternoon. Warm. High 76°. UV index up to 7. Wind east-southeast around 6 mph, gusting to 22 mph, in the morning, becoming 9 mph, gusting to 25 mph, in the afternoon. |
| Sunday night |
Partly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Scattered thundershowers possible. Breezy. Low 56°. Wind southeast around 10 mph, gusting to 20 mph, in the evening, becoming 13 mph, gusting to 18 mph, after midnight. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch. |
| Monday |
Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some possibly severe. Breezy and warm. High 81°. UV index up to 6. Wind south-southeast around 15 mph, gusting to 31 mph, in the morning, becoming south-southwest in the afternoon. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Monday night |
Partly to mostly cloudy in the evening, becoming clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 55°. Wind west-northwest around 10 mph, gusting to 26 mph. |
| Tuesday |
Sunny. Moderate fog in the morning. High 69°. UV index up to 9. Wind north-northwest around 5 mph, gusting to 24 mph. |
| Tuesday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. Low 53°. Wind east-southeast around 3 mph, gusting to 17 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.