| WXSIM Forecast for:
O'Fallon Issued by: OFallonweather.com |
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| Updated: Wednesday, 09-Sep-2026 04:00 pm | ||||||||||||||||||||||||||||||||||||||||||||||||
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| Tonight |
Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Rain. Precipitation showery or intermittent. Warm. Low 74°. Wind northeast around 3 mph, gusting to 16 mph. Chance of precipitation 90 percent. Precipitation mostly around half an inch. |
| Thursday |
Dense overcast in the morning, becoming cloudy in the afternoon. Light to moderate fog in the morning, then patchy light fog in the afternoon. Rain likely in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. High 80°. Wind east around 3 mph, gusting to 19 mph, in the morning, becoming north-northwest in the afternoon. Chance of precipitation 80 percent. Precipitation mostly between a quarter and half an inch. |
| Thursday night |
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Warm. Low 70°. Wind north-northeast around 2 mph, gusting to 18 mph. |
| Friday |
Mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A chance of rain. Warm. High 84°. UV index up to 6. Wind east-southeast around 3 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch. |
| Friday night |
Clear in the evening, becoming fair to partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Low 69°. Wind east-southeast around 4 mph, gusting to 16 mph, in the evening, becoming south after midnight. |
| Saturday |
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 89°. Heat index up to 95°. UV index up to 7. Wind southwest around 5 mph, gusting to 21 mph. |
| Saturday night |
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 68°. Wind west-northwest around 2 mph in the evening, becoming north-northeast after midnight. |
| Sunday |
Partly to mostly cloudy. Patchy light fog in the morning. Hot. High 87°. Heat index up to 93°. UV index up to 5. Wind east-southeast around 4 mph, gusting to 17 mph, in the morning, becoming south in the afternoon. |
| Sunday night |
Partly to mostly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Warm. Low 72°. Wind south around 6 mph. |
| Monday |
Sunny. Patchy light fog in the morning. Very hot. High 92°. Heat index up to 101°. UV index up to 7. Wind south around 7 mph, gusting to 23 mph. |
| Monday night |
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Warm. Low 73°. Wind south-southwest around 6 mph, gusting to 15 mph. |
| Tuesday |
Mostly cloudy. Patchy light fog in the morning. Rain likely. Precipitation showery or intermittent. Hot. High 86°. UV index up to 5. Wind north-northwest around 4 mph, gusting to 24 mph. Chance of precipitation 70 percent. Precipitation mostly less than 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 slight chance of rain after midnight. Precipitation showery or intermittent. Low 68°. Wind north around 5 mph, gusting to 21 mph. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch. |
WXSIM forecast formatting script by Saratoga-Weather.org.
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