| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Friday, 03-Jul-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. Very hot. High 98°. Heat index up to 110°. UV index up to 8. Wind southwest around 5 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Tonight |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Low 78°. Wind east-northeast around 3 mph, gusting to 15 mph, in the evening, becoming southeast after midnight. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Saturday |
Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 94°. Heat index up to 109°. UV index up to 9. Wind south around 5 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. A slight chance of rain after midnight. Precipitation showery or intermittent. Low 76°. Wind south around 2 mph, gusting to 21 mph, in the evening, becoming west-southwest after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Partly cloudy. Light to moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. High 90°. Heat index up to 100°. UV index up to 9. Wind west-northwest around 4 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Sunday night |
Fair to partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. A slight chance of rain. Scattered thundershowers possible. Low 73°. Wind northwest around 3 mph, gusting to 17 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Partly to mostly sunny. Moderate fog in the morning. A chance of rain. High 89°. Heat index up to 97°. UV index up to 8. Wind north-northeast around 3 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Partly cloudy in the evening, becoming fair after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 71°. Wind north around 2 mph, gusting to 16 mph. |
| Tuesday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. High 89°. Heat index up to 96°. UV index up to 8. Wind northeast around 4 mph, gusting to 22 mph. |
| Tuesday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. Low 71°. Wind east-northeast around 3 mph, gusting to 21 mph. |
| Wednesday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 91°. Heat index up to 98°. UV index up to 8. Wind southeast around 4 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Wednesday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Moderate fog. Low 73°. Wind southeast around 5 mph, gusting to 17 mph, in the evening, becoming south-southwest after midnight. |
| Thursday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Very hot. High 96°. Heat index up to 105°. UV index up to 10. Wind south-southwest around 10 mph, gusting to 27 mph. |
| Thursday night |
Partly cloudy in the evening, becoming mostly clear after midnight. Low 72°. Wind southwest around 4 mph, gusting to 21 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.