| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Tuesday, 22-Sep-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 54°. Wind north-northeast around 6 mph, gusting to 17 mph. |
| Wednesday |
Mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. High 72°. UV index up to 5. Wind north-northeast around 6 mph, gusting to 24 mph. |
| Wednesday night |
Fair to partly cloudy. Patchy light fog after midnight. Low 52°. Wind north-northeast around 4 mph, gusting to 20 mph. |
| Thursday |
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. High 74°. UV index up to 6. Wind north-northeast around 4 mph, gusting to 22 mph. |
| Thursday night |
Mostly cloudy in the evening, becoming partly cloudy after midnight. Low 55°. Wind northeast around 3 mph, gusting to 17 mph. |
| Friday |
Partly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. High 75°. UV index up to 4. Wind east-northeast around 4 mph, gusting to 20 mph. |
| Friday night |
Mostly cloudy to cloudy in the evening, becoming mostly cloudy after midnight. Low 57°. Wind east-northeast around 5 mph, gusting to 15 mph. |
| Saturday |
Cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. High 74°. UV index up to 5. Wind east-southeast around 5 mph, gusting to 22 mph. |
| Saturday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Low 57°. Wind east-southeast around 5 mph, gusting to 19 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch. |
| Sunday |
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 76°. UV index up to 4. Wind east-southeast around 4 mph, gusting to 18 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Sunday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain. Low 57°. Wind east around 4 mph, gusting to 15 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Partly to mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Warm. High 79°. UV index up to 5. Wind east around 5 mph, gusting to 23 mph. |
| Monday night |
Mostly clear in the evening, becoming partly to mostly cloudy after midnight. Low 57°. Wind east around 4 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.