| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 23-Sep-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 54°. Wind northeast around 4 mph, gusting to 20 mph. |
| Thursday |
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. High 75°. UV index up to 6. Wind northeast around 4 mph, gusting to 23 mph. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 55°. Wind northeast around 2 mph, gusting to 17 mph. |
| Friday |
Cloudy in the morning, becoming mostly cloudy in the afternoon. High 74°. UV index up to 4. Wind east around 3 mph, gusting to 21 mph. |
| Friday night |
Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. A chance of rain. Low 59°. Wind east around 5 mph, gusting to 18 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch. |
| Saturday |
Dense overcast. Patchy light fog in the morning. Rain likely. High 66°. Wind east around 3 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Saturday night |
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog after midnight. A chance of rain. Low 58°. Wind east around 4 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch. |
| Sunday |
Mostly cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely. High 71°. UV index up to 5. Wind east around 4 mph, gusting to 20 mph. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch. |
| Sunday night |
Fair to partly cloudy in the evening, becoming mostly cloudy after midnight. Light to moderate fog. A slight chance of rain. Low 59°. Wind east around 3 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch. |
| Monday |
Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. High 76°. UV index up to 6. Wind east around 4 mph, gusting to 21 mph. |
| Monday night |
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. Low 58°. Wind east around 3 mph, gusting to 15 mph. |
| Tuesday |
Mostly cloudy to cloudy in the morning, becoming cloudy in the afternoon. 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. Warm. High 78°. Wind southeast around 7 mph, gusting to 20 mph, in the morning, becoming south around 11 mph, gusting to 23 mph, in the afternoon. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch. |
| Tuesday night |
Dense overcast in the evening, becoming cloudy after midnight. Patchy light fog. Rain likely in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 63°. Wind southwest around 11 mph, gusting to 19 mph, in the evening, becoming northwest around 7 mph, gusting to 19 mph, after midnight. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.