| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 15-Jun-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair to partly cloudy. Relatively cool. Low 59°. Wind south-southwest around 4 mph, gusting to 22 mph. |
| Tuesday |
Partly to 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. High 82°. UV index up to 7. Wind south-southwest around 9 mph, gusting to 28 mph, in the morning, becoming west in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Fair in the evening, becoming fair to partly cloudy after midnight. Light to moderate fog after midnight. Relatively cool. Low 61°. Wind west around 4 mph, gusting to 22 mph, in the evening, becoming southeast after midnight. |
| Wednesday |
Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. A chance of rain. Scattered thundershowers possible. Breezy and hot. High 90°. Heat index up to 94°. UV index up to 9. Wind south around 9 mph, gusting to 26 mph, in the morning, becoming 17 mph, gusting to 33 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday night |
Mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. Rain likely in the evening, then a slight chance of rain after midnight. Thunderstorms very likely, some possibly severe. Breezy. Low 70°. Wind southwest around 15 mph, gusting to 28 mph, in the evening, becoming 10 mph, gusting to 20 mph, after midnight. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Thursday |
Partly cloudy. Light to moderate fog in the morning. A chance of rain. High 84°. UV index up to 8. Wind west around 7 mph, gusting to 26 mph, in the morning, becoming north-northwest in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Fair in the evening, becoming partly cloudy after midnight. Patchy light fog. A slight chance of rain in the evening. Relatively cool. Low 64°. Wind north-northwest around 2 mph, gusting to 19 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Friday |
Partly to mostly cloudy. Patchy light fog in the morning. High 82°. UV index up to 8. Wind northwest around 5 mph, gusting to 24 mph. |
| Friday night |
Fair to partly cloudy in the evening, becoming clear after midnight. Relatively cool. Low 61°. Wind northeast around 3 mph, gusting to 22 mph, in the evening, becoming south-southeast after midnight. |
| Saturday |
Sunny. Hot. High 88°. UV index up to 9. Wind south around 6 mph, gusting to 25 mph. |
| Saturday night |
Partly cloudy. Low 66°. Wind south around 8 mph, gusting to 21 mph. |
| Sunday |
Mostly cloudy to cloudy. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. High 84°. UV index up to 6. Wind south around 11 mph, gusting to 27 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Moderate fog. A chance of rain in the evening, then rain likely after midnight. Thunderstorms very likely, some possibly severe. Low 71°. Wind south-southwest around 7 mph, gusting to 16 mph. Chance of precipitation 80 percent. Precipitation mostly around an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.