| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Sunday, 07-Jun-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. A chance of rain. Scattered thundershowers possible. Hot. High 89°. Heat index up to 94°. UV index up to 8. Wind southeast around 4 mph, gusting to 24 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tonight |
Cloudy in the evening, becoming dense overcast after midnight. Patchy light fog after midnight. Rain likely. Scattered thunderstorms likely. Warm. Low 76°. Wind southeast around 8 mph, gusting to 24 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Monday |
Mostly cloudy. Patchy light fog in the morning. Rain likely. Scattered thunderstorms likely. High 84°. UV index up to 5. Wind south around 7 mph, gusting to 25 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Monday night |
Mostly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely. Scattered thundershowers possible. Low 74°. Wind south-southwest around 5 mph, gusting to 21 mph. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch. |
| Tuesday |
Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Moderate fog in the morning. A slight chance of rain. Scattered thundershowers possible. Hot. High 91°. Heat index up to 101°. UV index up to 9. Wind south-southwest around 4 mph, gusting to 23 mph, in the morning, becoming 7 mph, gusting to 25 mph, in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Fair in the evening, becoming clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 74°. Wind south-southwest around 5 mph, gusting to 20 mph. |
| Wednesday |
Sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. Hot. High 93°. Heat index up to 103°. UV index up to 8. Wind south-southwest around 10 mph, gusting to 28 mph. |
| Wednesday night |
Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 75°. Wind south-southwest around 8 mph, gusting to 23 mph. |
| Thursday |
Sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 95°. Heat index up to 105°. UV index up to 9. Wind south-southwest around 10 mph, gusting to 29 mph. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Scattered thunderstorms likely. Low 72°. Wind south-southwest around 7 mph, gusting to 25 mph, in the evening, becoming northwest after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday |
Sunny. Patchy light fog in the morning. Hot. High 87°. Heat index up to 92°. UV index up to 9. Wind northwest around 5 mph, gusting to 24 mph. |
| Friday night |
Clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 67°. Wind east-northeast around 3 mph, gusting to 19 mph, in the evening, becoming southeast after midnight. |
| Saturday |
Mostly cloudy. Patchy light fog in the morning. Rain likely. Scattered thundershowers possible. High 81°. UV index up to 5. Wind south-southeast around 2 mph, gusting to 15 mph. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch. |
| Saturday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then rain likely after midnight. Scattered thundershowers possible. Low 69°. Wind south around 5 mph in the evening, becoming northwest after midnight. Chance of precipitation 70 percent. Precipitation mostly around half an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.