WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Wednesday, 07-Oct-2026 04:00 pm
 
Tonight

Fog late
Fog late
Thursday

Fog a.m.
Fog a.m.
Thursday
night
Clear
Clear
Friday

Sunny
Sunny
Friday
night
Mostly Clear
Mostly Clear
Saturday

Partly Cloudy
Partly Cloudy
Saturday
night
Chance rain
Chance rain
Sunday

Chance rain
Chance rain
<.25 in. <.1 in.
Low: 57° High: 82° Low: 54° High: 85° Low: 55° High: 84° Low: 60° High: 79°
               
NNW
4-24
mph
E
2-21
mph
SE
3
mph
SSE
6-23
mph
SSE
5-15
mph
SSE
6-24
mph
ESE
4-16
mph
NE→N
4-23
mph
UV: 5
 Medium 
UV: 5
 Medium 
UV: 5
 Medium 
UV: 5
 Medium 

 

Tonight
 
Clear. Patchy light fog after midnight. Low 57°. Wind north-northwest around 4 mph, gusting to 24 mph.
Thursday
 
Sunny. Patchy light fog in the morning. Unusually hot. High 82°. UV index up to 5. Wind east around 2 mph, gusting to 21 mph.
Thursday night
 
Clear. Low 54°. Wind southeast around 3 mph.
Friday
 
Sunny. Unusually hot. High 85°. UV index up to 5. Wind south-southeast around 6 mph, gusting to 23 mph.
Friday night
 
Clear in the evening, becoming mostly clear after midnight. Low 55°. Wind south-southeast around 5 mph, gusting to 15 mph.
Saturday
 
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Unusually hot. High 84°. UV index up to 5. Wind south-southeast around 6 mph, gusting to 24 mph.
Saturday night
 
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. A chance of rain after midnight. Low 60°. Wind east-southeast around 4 mph, gusting to 16 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Sunday
 
Partly to mostly sunny. Moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Warm. High 79°. UV index up to 5. Wind northeast around 4 mph, gusting to 23 mph, in the morning, becoming north in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday night
 
Partly cloudy in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 56°. Wind south around 3 mph.
Monday
 
Sunny. Patchy light fog in the morning. Unusually hot. High 85°. UV index up to 5. Wind southwest around 6 mph, gusting to 20 mph.
Monday night
 
Clear. Low 59°. Wind southwest around 7 mph.
Tuesday
 
Partly to mostly sunny in the morning, becoming mostly 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 78°. Wind north-northwest around 5 mph, gusting to 20 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night
 
Fair to partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 53°. Wind east-northeast around 7 mph, gusting to 15 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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