| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 15-Jul-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Fair to partly cloudy. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Low 75°. Wind east around 2 mph, gusting to 20 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Thursday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. Precipitation showery or intermittent. High 90°. Heat index up to 99°. UV index up to 8. Wind northeast around 2 mph, gusting to 19 mph, in the morning, becoming southeast in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday night |
Partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain. Precipitation showery or intermittent. Low 75°. Wind southwest around 3 mph, gusting to 15 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch. |
| Friday |
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Precipitation showery or intermittent. High 89°. Heat index up to 99°. UV index up to 9. Wind southwest around 5 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Fair to partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Low 74°. Wind southwest around 5 mph, gusting to 19 mph. |
| Saturday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Moderate fog in the morning. Hot. High 95°. Heat index up to 104°. UV index up to 9. Wind west-southwest around 8 mph, gusting to 26 mph. |
| Saturday night |
Partly cloudy. Patchy light fog after midnight. A chance of rain. Low 75°. Wind west-southwest around 5 mph, gusting to 21 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday |
Partly to mostly cloudy. Patchy light fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. High 89°. Heat index up to 98°. UV index up to 7. Wind north-northeast around 3 mph, gusting to 20 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 72°. Wind northeast around 4 mph, gusting to 19 mph, in the evening, becoming east after midnight. |
| Monday |
Partly to mostly cloudy. Patchy light 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 8. Wind south-southeast around 3 mph, gusting to 18 mph, in the morning, becoming south-southwest in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Fair in the evening, becoming mostly clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 74°. Wind southwest around 4 mph, gusting to 15 mph. |
| Tuesday |
Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. Very hot. High 97°. Heat index up to 107°. UV index up to 7. Wind west around 7 mph, gusting to 24 mph. |
| Tuesday night |
Partly cloudy. Low 72°. Wind north-northwest around 3 mph, gusting to 18 mph, in the evening, becoming northeast after midnight. |
WXSIM forecast formatting script by Saratoga-Weather.org.
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