| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 29-Jul-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Hot. High 90°. Heat index up to 94°. UV index up to 9. Wind east around 5 mph, gusting to 25 mph, in the morning, becoming northeast in the afternoon. |
| Tonight |
Fair. Relatively cool. Low 66°. Wind northeast around 4 mph, gusting to 23 mph. |
| Thursday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. A chance of rain. High 87°. UV index up to 8. Wind east around 5 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Partly cloudy. Low 69°. Wind east around 6 mph, gusting to 20 mph, in the evening, becoming southeast after midnight. |
| Friday |
Mostly cloudy to cloudy. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. High 84°. UV index up to 5. Wind southeast around 7 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Friday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog in the evening, then patchy light fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 73°. Wind south around 7 mph, gusting to 20 mph, in the evening, becoming west after midnight. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Saturday |
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. High 83°. UV index up to 6. Wind northwest around 10 mph, gusting to 28 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain. Low 68°. Wind north-northwest around 8 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Sunny. Moderate fog in the morning. High 83°. UV index up to 8. Wind north-northeast around 9 mph, gusting to 26 mph. |
| Sunday night |
Mostly clear. Patchy light fog after midnight. Relatively cool. Low 65°. Wind north-northeast around 4 mph, gusting to 23 mph. |
| Monday |
Sunny. Patchy light fog in the morning. High 86°. UV index up to 8. Wind north-northeast around 4 mph, gusting to 23 mph. |
| Monday night |
Clear. Patchy light fog after midnight. Relatively cool. Low 64°. Wind east around 4 mph, gusting to 19 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. High 89°. Heat index up to 92°. UV index up to 9. Wind southeast around 5 mph, gusting to 23 mph. |
| Tuesday night |
Clear. Patchy light fog after midnight. Low 68°. Wind east around 7 mph, gusting to 22 mph, in the evening, becoming 4 mph after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.