| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Monday, 21-Sep-2026 05:00 am | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Today |
Cloudy. A slight chance of rain. Scattered thundershowers possible. High 78°. Wind north around 5 mph, gusting to 24 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Tonight |
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 63°. Wind north around 5 mph, gusting to 22 mph. |
| Tuesday |
Mostly cloudy to cloudy. A chance of rain. High 72°. Wind north around 6 mph, gusting to 24 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Tuesday night |
Mostly cloudy to cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 55°. Wind north-northeast around 6 mph, gusting to 24 mph. |
| Wednesday |
Mostly sunny in the morning, becoming partly cloudy in the afternoon. High 74°. UV index up to 5. Wind north-northeast around 7 mph, gusting to 25 mph. |
| Wednesday night |
Fair in the evening, becoming partly cloudy after midnight. Low 53°. Wind north-northeast around 4 mph, gusting to 20 mph. |
| Thursday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. High 76°. UV index up to 6. Wind northeast around 5 mph, gusting to 24 mph. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 55°. Wind northeast around 3 mph, gusting to 19 mph. |
| Friday |
Mostly cloudy. High 76°. UV index up to 4. Wind east-northeast around 5 mph, gusting to 22 mph. |
| Friday night |
Partly cloudy. Low 55°. Wind east around 4 mph, gusting to 18 mph. |
| Saturday |
Mostly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. High 74°. Wind east-southeast around 4 mph, gusting to 20 mph. |
| Saturday night |
Partly to mostly cloudy. Patchy light fog after midnight. Low 56°. Wind southeast around 5 mph, gusting to 16 mph. |
| Sunday |
Partly cloudy in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. High 78°. UV index up to 5. Wind east-southeast around 7 mph, gusting to 24 mph. |
| Sunday night |
Clear. Light to moderate fog after midnight. Low 54°. Wind east-northeast around 5 mph, gusting to 19 mph. |
WXSIM forecast formatting script by Saratoga-Weather.org.