| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 13-May-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Clear. Cool. Low 48°. Wind north-northwest around 3 mph, gusting to 23 mph, in the evening, becoming east-northeast after midnight. |
| Thursday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. High 76°. UV index up to 7. Wind southeast around 4 mph, gusting to 24 mph. |
| Thursday night |
Mostly cloudy in the evening, becoming partly cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Cool. Low 51°. Wind southeast around 8 mph, gusting to 21 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Friday |
Partly to mostly cloudy. Patchy light fog in the morning. A chance of rain. Scattered thundershowers possible. Warm. High 82°. UV index up to 6. Wind southeast around 8 mph, gusting to 24 mph, in the morning, becoming south-southwest in the afternoon. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch. |
| Friday night |
Partly cloudy. A chance of rain. Scattered thundershowers possible. Low 60°. Wind south around 6 mph, gusting to 21 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday |
Mostly cloudy to cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning, then light to moderate fog in the afternoon. A chance of rain in the morning, then rain likely in the afternoon. Scattered thundershowers possible. High 79°. UV index up to 7. Wind south-southwest around 4 mph, gusting to 17 mph. Chance of precipitation 70 percent. Precipitation mostly around half an inch. |
| Saturday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 63°. Wind southeast around 4 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Partly to mostly cloudy. Moderate fog in the morning. A slight chance of rain in the morning. Scattered thunderstorms likely. Warm. High 84°. UV index up to 6. Wind south around 7 mph, gusting to 20 mph, in the morning, becoming 12 mph, gusting to 26 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Clear in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Low 66°. Wind south around 11 mph, gusting to 23 mph. |
| Monday |
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the morning, then rain likely in the afternoon. Thunderstorms very likely, some possibly severe. Breezy and warm. High 83°. UV index up to 7. Wind south around 12 mph, gusting to 26 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Monday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely. Thunderstorms very likely, some possibly severe. Warm. Low 72°. Wind south around 12 mph, gusting to 23 mph, in the evening, becoming 6 mph, gusting to 17 mph, after midnight. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch. |
| Tuesday |
Cloudy in the morning, becoming dense overcast in the afternoon. Patchy light fog in the morning. High 76°. UV index up to 4. Wind east-southeast around 5 mph, gusting to 24 mph, in the morning, becoming northeast in the afternoon. |
| Tuesday night |
Partly cloudy in the evening, becoming fair after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 63°. Wind east-northeast around 4 mph, gusting to 20 mph, in the evening, becoming east-southeast after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.