| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 11-May-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Sunny. High 79°. UV index up to 7. Wind west around 6 mph, gusting to 25 mph. |
| Tonight |
Mostly clear in the evening, becoming fair after midnight. Cool. Low 49°. Wind west-southwest around 3 mph, gusting to 20 mph, in the evening, becoming south after midnight. |
| Tuesday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. A slight chance of rain in the afternoon. Precipitation showery or intermittent. Hot. High 85°. UV index up to 8. Wind southwest around 8 mph, gusting to 27 mph, in the morning, becoming 12 mph, gusting to 30 mph, in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Partly to mostly cloudy in the evening, becoming clear after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 57°. Wind west-northwest around 7 mph, gusting to 21 mph. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch. |
| Wednesday |
Sunny. Patchy light fog in the morning. High 75°. UV index up to 7. Wind northwest around 8 mph, gusting to 28 mph, in the morning, becoming 11 mph, gusting to 29 mph, in the afternoon. |
| Wednesday night |
Clear. Cool. Low 50°. Wind north-northwest around 5 mph, gusting to 24 mph, in the evening, becoming northeast after midnight. |
| Thursday |
Sunny in the morning, becoming mostly sunny in the afternoon. High 75°. UV index up to 7. Wind east-northeast around 3 mph, gusting to 23 mph. |
| Thursday night |
Fair in the evening, becoming partly cloudy after midnight. Cool. Low 51°. Wind east-southeast around 6 mph, gusting to 19 mph. |
| Friday |
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. Breezy and warm. High 80°. UV index up to 5. Wind south-southeast around 10 mph, gusting to 28 mph, in the morning, becoming 14 mph, gusting to 31 mph, in the afternoon. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Friday night |
Fair to partly cloudy. Low 62°. Wind south around 9 mph, gusting to 26 mph. |
| Saturday |
Cloudy. A slight chance of rain in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some severe. Warm. High 81°. Wind southwest around 9 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Saturday night |
Partly cloudy in the evening, becoming mostly cloudy after midnight. A chance of rain. Scattered thunderstorms likely. Low 66°. Wind southwest around 3 mph, gusting to 16 mph, in the evening, becoming southeast after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Mostly cloudy in the morning, becoming partly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. Warm. High 83°. UV index up to 8. Wind south-southeast around 8 mph, gusting to 28 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Sunday night |
Mostly cloudy to cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Thunderstorms very likely, some possibly severe. Warm. Low 69°. Wind south around 5 mph, gusting to 21 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.