| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 15-Jul-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Hot. High 92°. UV index up to 9. Wind northeast around 3 mph, gusting to 22 mph. |
| Tonight |
Fair to partly cloudy. Light to moderate fog after midnight. A chance of rain. Low 70°. Wind east-northeast around 2 mph in the evening, becoming southeast after midnight. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Thursday |
Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thundershowers possible. High 88°. Heat index up to 94°. UV index up to 8. Wind southeast around 2 mph, gusting to 17 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday night |
Mostly 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 a slight chance of rain after midnight. Scattered thundershowers possible. Low 74°. Wind south around 3 mph in the evening, becoming west-southwest after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday |
Partly cloudy in the morning, becoming mostly 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. High 88°. Heat index up to 94°. UV index up to 7. Wind west-southwest around 5 mph, gusting to 21 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Friday night |
Partly cloudy in the evening, becoming fair after midnight. Moderate fog. A chance of rain. Scattered thundershowers possible. Low 75°. Wind west-southwest around 5 mph, gusting to 15 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday |
Partly to mostly sunny. Moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 92°. Heat index up to 103°. UV index up to 9. Wind west-southwest around 8 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday night |
Fair in the evening, becoming partly cloudy after midnight. Moderate fog after midnight. Low 74°. Wind west around 6 mph, gusting to 19 mph. |
| Sunday |
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. High 90°. Heat index up to 98°. UV index up to 9. Wind northwest around 4 mph, gusting to 19 mph, in the morning, becoming northeast in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Partly cloudy. Patchy light fog in the evening, then light to moderate fog after midnight. A slight chance of rain. Low 73°. Wind east around 3 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Hot. High 94°. Heat index up to 105°. UV index up to 8. Wind south-southwest around 5 mph, gusting to 22 mph. |
| Monday night |
Partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Low 71°. Wind north-northwest around 6 mph, gusting to 17 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Tuesday |
Sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. High 86°. UV index up to 9. Wind north-northwest around 7 mph, gusting to 27 mph. |
| Tuesday night |
Partly cloudy. Low 68°. Wind north-northeast around 2 mph, gusting to 22 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.