| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Friday, 31-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Moderate fog. Rain likely in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 72°. Wind south around 8 mph, gusting to 23 mph, in the evening, becoming west-southwest after midnight. Chance of precipitation 80 percent. Precipitation mostly around half an inch. |
| Saturday |
Cloudy. Patchy light fog in the morning. Rain likely. Scattered thundershowers possible. Relatively cool. High 78°. Wind west around 9 mph, gusting to 27 mph, in the morning, becoming northwest in the afternoon. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch. |
| Saturday night |
Dense overcast in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog. Rain likely. Scattered thundershowers possible. Breezy. Low 69°. Wind northwest around 12 mph, gusting to 28 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Sunday |
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 80°. UV index up to 6. Wind north-northwest around 11 mph, gusting to 27 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Mostly clear in the evening, becoming clear after midnight. Light to moderate fog after midnight. Relatively cool. Low 64°. Wind north around 5 mph, gusting to 23 mph. |
| Monday |
Sunny. Light to moderate fog in the morning. High 85°. UV index up to 9. Wind north around 4 mph, gusting to 23 mph. |
| Monday night |
Mostly clear in the evening, becoming clear after midnight. Patchy light fog after midnight. Relatively cool. Low 65°. Wind east-northeast around 3 mph, gusting to 18 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. High 86°. UV index up to 9. Wind northeast around 2 mph, gusting to 22 mph. |
| Tuesday night |
Mostly clear in the evening, becoming clear after midnight. Patchy light fog after midnight. Relatively cool. Low 66°. Wind east-northeast around 3 mph, gusting to 17 mph, in the evening, becoming southeast after midnight. |
| Wednesday |
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. High 89°. Heat index up to 93°. UV index up to 8. Wind southeast around 4 mph, gusting to 21 mph. |
| Wednesday night |
Partly cloudy. Light to moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 70°. Wind east-northeast around 4 mph, gusting to 19 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Thursday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 90°. Heat index up to 97°. UV index up to 9. Wind southeast around 5 mph, gusting to 18 mph, in the morning, becoming 8 mph, gusting to 22 mph, in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday night |
Partly cloudy in the evening, becoming mostly cloudy after midnight. Moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 72°. Wind south-southeast around 10 mph, gusting to 18 mph, in the evening, becoming 4 mph after midnight. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.