| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 22-Jul-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. A chance of rain. High 84°. UV index up to 8. Wind north around 6 mph, gusting to 25 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tonight |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Unusually cool. Low 62°. Wind north-northeast around 5 mph, gusting to 20 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday |
Partly cloudy. Patchy light fog in the morning. A chance of rain. High 81°. UV index up to 7. Wind east around 5 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Thursday night |
Partly to mostly cloudy. Patchy light fog after midnight. A chance of rain. Relatively cool. Low 65°. Wind east around 4 mph, gusting to 19 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Friday |
Cloudy in the morning, becoming dense overcast in the afternoon. Rain likely. Relatively cool. High 77°. UV index up to 4. Wind east-southeast around 5 mph, gusting to 20 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Friday night |
Mostly cloudy to cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then rain likely after midnight. Relatively cool. Low 66°. Wind east-southeast around 6 mph, gusting to 18 mph. Chance of precipitation 70 percent. Precipitation mostly between half an inch and one inch. |
| Saturday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 89°. Heat index up to 95°. UV index up to 9. Wind southeast around 5 mph, gusting to 21 mph, in the morning, becoming south in the afternoon. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch. |
| Saturday night |
Mostly clear in the evening, becoming partly cloudy after midnight. Low 71°. Wind east-southeast around 3 mph, gusting to 19 mph. |
| Sunday |
Partly cloudy. Hot. High 93°. Heat index up to 102°. UV index up to 7. Wind west-southwest around 3 mph, gusting to 20 mph, in the morning, becoming southeast in the afternoon. |
| Sunday night |
Fair in the evening, becoming partly cloudy after midnight. Low 73°. Wind south-southeast around 3 mph, gusting to 16 mph. |
| Monday |
Sunny. Patchy light fog in the morning. Hot. High 95°. Heat index up to 105°. UV index up to 9. Wind south-southwest around 7 mph, gusting to 22 mph. |
| Monday night |
Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 74°. Wind southwest around 5 mph, gusting to 15 mph. |
| Tuesday |
Sunny. Patchy light fog in the morning. Very hot. High 98°. Heat index up to 110°. UV index up to 9. Wind southwest around 11 mph, gusting to 25 mph. |
| Tuesday night |
Fair to partly cloudy in the evening, becoming clear after midnight. Low 76°. Wind west around 6 mph, gusting to 19 mph, in the evening, becoming 3 mph after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.