WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Friday, 05-Dec-2025 04:00 pm
 
Tonight

Fog late
Fog late
Saturday

Fog a.m.
Fog a.m.
Saturday
night
Rain and Snow
Rain and Snow
Sunday

Fog a.m.
Fog a.m.
Sunday
night
Partly Cloudy
Partly Cloudy
Monday

Mostly Sunny
Mostly Sunny
Monday
night
Partly Cloudy
Partly Cloudy
Tuesday

Mostly Sunny
Mostly Sunny
<.1 in.
Low: 27° High: 43° Low: 32° High: 35° Low: 18° High: 39° Low: 23° High: 51°
            WCh: 14°  
SSW→W
6-23
mph
W→ESE
2
mph
SE
5
mph
N
5-18→10-24
mph
N
6-23
mph
NNE→S
2-18
mph
SSE→SSW
4→8
mph
SSW
9-22
mph

 

Tonight
 
Mostly cloudy to cloudy. Patchy light fog after midnight. Low 27°. Wind south-southwest around 6 mph, gusting to 23 mph, in the evening, becoming west after midnight.
Saturday
 
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. High 43°. Wind west around 2 mph in the morning, becoming east-southeast in the afternoon.
Saturday night
 
Cloudy. Patchy light fog after midnight. A slight chance of a mix of rain and snow. Low 32°. Wind southeast around 5 mph. Chance of precipitation 20 percent. Precipitation (liquid equivalent) mostly less than a tenth of an inch. No snow accumulation expected.
Sunday
 
Mostly cloudy to cloudy. Patchy light fog in the morning. High 35°. Wind north around 5 mph, gusting to 18 mph, in the morning, becoming 10 mph, gusting to 24 mph, in the afternoon.
Sunday night
 
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 18°. Wind north around 6 mph, gusting to 23 mph.
Monday
 
Mostly sunny in the morning, becoming sunny in the afternoon. High 39°. Wind north-northeast around 2 mph, gusting to 18 mph, in the morning, becoming south in the afternoon.
Monday night
 
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Low 23°. Wind chill ranging from 14 to 31. Wind south-southeast around 4 mph in the evening, becoming south-southwest around 8 mph after midnight.
Tuesday
 
Partly to mostly sunny. Relatively mild. High 51°. Wind south-southwest around 9 mph, gusting to 22 mph.
Tuesday night
 
Partly to mostly cloudy. Breezy. Low 32°. Wind chill ranging from 24 to 37. Wind southwest around 12 mph, gusting to 17 mph.
Wednesday
 
Partly cloudy in the morning, becoming mostly cloudy in the afternoon. Breezy. High 42°. Wind west-northwest around 14 mph, gusting to 25 mph, in the morning, becoming 10 mph, gusting to 26 mph, in the afternoon.
Wednesday night
 
Partly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 27°. Wind northwest around 2 mph, gusting to 20 mph, in the evening, becoming east after midnight.
Thursday
 
Mostly cloudy in the morning, becoming partly cloudy in the afternoon. Relatively mild. High 53°. Wind east-southeast around 7 mph, gusting to 20 mph, in the morning, becoming south around 12 mph, gusting to 24 mph, in the afternoon.
Thursday night
 
Mostly clear in the evening, becoming partly to mostly cloudy after midnight. Breezy. Low 28°. Wind chill ranging from 20 to 44. Wind west-southwest around 12 mph, gusting to 22 mph, in the evening, becoming northwest after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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