| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Sunday, 27-Sep-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly to mostly cloudy. Patchy light fog after midnight. Low 55°. Wind northeast around 3 mph, gusting to 16 mph. |
| Monday |
Partly cloudy in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. High 76°. UV index up to 6. Wind northeast around 3 mph, gusting to 20 mph. |
| Monday night |
Clear. Patchy light fog after midnight. Low 52°. Wind northeast around 2 mph in the evening, becoming southeast after midnight. |
| Tuesday |
Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Warm. High 80°. UV index up to 6. Wind south-southeast around 5 mph, gusting to 22 mph. |
| Tuesday night |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Low 55°. Wind south-southeast around 5 mph. |
| Wednesday |
Partly cloudy. Warm. High 84°. UV index up to 5. Wind south-southeast around 7 mph, gusting to 20 mph. |
| Wednesday night |
Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 62°. Wind south around 6 mph. |
| Thursday |
Mostly cloudy to cloudy in the morning, becoming cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. Warm. High 79°. Wind south-southwest around 4 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Thursday night |
Dense overcast. Light to moderate fog in the evening, then patchy light fog after midnight. Rain likely. Precipitation showery or intermittent. Low 63°. Wind north around 6 mph, gusting to 19 mph. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch. |
| Friday |
Cloudy in the morning, becoming partly to mostly sunny in the afternoon. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 74°. UV index up to 7. Wind north around 8 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Mostly clear. Patchy light fog after midnight. Low 52°. Wind north-northeast around 6 mph, gusting to 22 mph. |
| Saturday |
Sunny. Light to moderate fog in the morning. High 69°. UV index up to 5. Wind northeast around 8 mph, gusting to 26 mph. |
| Saturday night |
Partly cloudy in the evening, becoming mostly cloudy after midnight. Low 53°. Wind east-northeast around 5 mph, gusting to 19 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.