| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Sunday, 20-Sep-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Mostly cloudy to cloudy in the evening, becoming dense overcast after midnight. Patchy light fog. Rain likely. Precipitation showery or intermittent. Warm. Low 71°. Wind north-northeast around 6 mph, gusting to 20 mph, in the evening, becoming 3 mph after midnight. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Monday |
Cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. A chance of rain. Precipitation showery or intermittent. High 77°. Wind north-northeast around 4 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Monday night |
Mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 66°. Wind north-northeast around 5 mph, gusting to 22 mph. |
| Tuesday |
Cloudy in the morning, becoming mostly cloudy in the afternoon. High 75°. Wind north-northeast around 6 mph, gusting to 25 mph. |
| Tuesday night |
Mostly cloudy to cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 57°. Wind northeast around 6 mph, gusting to 24 mph. |
| Wednesday |
Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. High 74°. UV index up to 6. Wind northeast around 6 mph, gusting to 24 mph. |
| Wednesday night |
Fair in the evening, becoming fair to partly cloudy after midnight. Low 53°. Wind north-northeast around 4 mph, gusting to 21 mph. |
| Thursday |
Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. High 76°. UV index up to 6. Wind north-northeast around 5 mph, gusting to 23 mph. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming fair after midnight. Low 54°. Wind north-northeast around 4 mph, gusting to 18 mph. |
| Friday |
Partly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. A slight chance of rain. High 73°. Wind east-northeast around 5 mph, gusting to 19 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 56°. Wind east-northeast around 4 mph, gusting to 16 mph. |
| Saturday |
Mostly cloudy. High 76°. Wind east-southeast around 6 mph, gusting to 23 mph. |
| Saturday night |
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 58°. Wind east-southeast around 4 mph, gusting to 20 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.