| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Friday, 17-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair. Moderate fog after midnight. Low 74°. Wind west-southwest around 5 mph, gusting to 24 mph. |
| Saturday |
Partly to mostly sunny. Moderate fog in the morning. A chance of rain. Precipitation showery or intermittent. Hot. High 91°. Heat index up to 100°. UV index up to 10. Wind southwest around 7 mph, gusting to 25 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Fair to partly cloudy. Moderate fog. A chance of rain. Low 75°. Wind west-southwest around 5 mph, gusting to 20 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Sunday |
Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Rain likely. Scattered thundershowers possible. Hot. High 91°. Heat index up to 101°. UV index up to 9. Wind northwest around 3 mph, gusting to 20 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch. |
| Sunday night |
Partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely. Scattered thundershowers possible. Low 76°. Wind east-southeast around 2 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch. |
| Monday |
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 93°. Heat index up to 105°. UV index up to 9. Wind south around 2 mph, gusting to 20 mph, in the morning, becoming west-southwest in the afternoon. |
| Monday night |
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Moderate fog after midnight. A chance of rain after midnight. Precipitation showery or intermittent. Low 74°. Wind south-southwest around 5 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Moderate fog in the morning. A slight chance of rain in the afternoon. Precipitation showery or intermittent. Hot. High 95°. Heat index up to 105°. UV index up to 9. Wind west-southwest around 7 mph, gusting to 23 mph, in the morning, becoming northwest in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Fair to partly cloudy. Patchy light fog after midnight. Low 70°. Wind north around 6 mph, gusting to 17 mph. |
| Wednesday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 87°. UV index up to 9. Wind north around 6 mph, gusting to 25 mph. |
| Wednesday night |
Partly cloudy. Relatively cool. Low 66°. Wind northeast around 4 mph, gusting to 21 mph. |
| Thursday |
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. High 87°. UV index up to 7. Wind south around 4 mph, gusting to 25 mph, in the morning, becoming southwest in the afternoon. |
| Thursday night |
Partly cloudy in the evening, becoming cloudy after midnight. Low 71°. Wind west-southwest around 2 mph, gusting to 23 mph, in the evening, becoming southeast after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.