WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Sunday, 12-Apr-2026 04:00 pm
 
Tonight

Fog
Fog
Monday

Fog a.m.
Fog a.m.
Monday
night
Clear
Clear
Tuesday

Sunny
Sunny
Tuesday
night
Clear
Clear
Wednesday

Sunny
Sunny
Wednesday
night
Clear
Clear
Thursday

Sunny
Sunny
Low: 49° High: 79° Low: 49° High: 82° Low: 50° High: 83° Low: 50° High: 83°
               
SSW
8-27
mph
SSW
10-29→15-31
mph
SSW
11-27
mph
SSW
13-30
mph
SSW
11-27
mph
SSW
13-30
mph
SSW
11-27
mph
SSW
13-30
mph
UV: 8
 Very High 
UV: 8
 Very High 
UV: 8
 Very High 
UV: 8
 Very High 

 

Tonight
 
Mostly clear in the evening, becoming clear after midnight. Patchy light fog. Low 49°. Wind south-southwest around 8 mph, gusting to 27 mph.
Monday
 
Sunny. Patchy light fog in the morning. Breezy and warm. High 79°. UV index up to 8. Wind south-southwest around 10 mph, gusting to 29 mph, in the morning, becoming 15 mph, gusting to 31 mph, in the afternoon.
Monday night
 
Clear. Low 49°. Wind south-southwest around 11 mph, gusting to 27 mph.
Tuesday
 
Sunny. Breezy and unusually hot. High 82°. UV index up to 8. Wind south-southwest around 13 mph, gusting to 30 mph.
Tuesday night
 
Clear. Low 50°. Wind south-southwest around 11 mph, gusting to 27 mph.
Wednesday
 
Sunny. Breezy and unusually hot. High 83°. UV index up to 8. Wind south-southwest around 13 mph, gusting to 30 mph.
Wednesday night
 
Clear. Low 50°. Wind south-southwest around 11 mph, gusting to 27 mph.
Thursday
 
Sunny. Breezy and unusually hot. High 83°. UV index up to 8. Wind south-southwest around 13 mph, gusting to 30 mph.
Thursday night
 
Clear. Low 50°. Wind south-southwest around 11 mph, gusting to 27 mph.
Friday
 
Sunny. Breezy and unusually hot. High 84°. UV index up to 8. Wind south-southwest around 13 mph, gusting to 30 mph.
Friday night
 
Clear. Low 50°. Wind south-southwest around 11 mph, gusting to 27 mph.
Saturday
 
Sunny. Breezy and unusually hot. High 84°. UV index up to 8. Wind south-southwest around 13 mph, gusting to 30 mph.
Saturday night
 
Clear. Low 50°. Wind south-southwest around 11 mph, gusting to 27 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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