WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Friday, 02-Oct-2026 04:00 pm
 
Tonight

Fog late
Fog late
Saturday

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

Sunny
Sunny
Sunday
night
Clear
Clear
Monday

Sunny
Sunny
Monday
night
Clear
Clear
Tuesday

Sunny
Sunny
Low: 51° High: 75° Low: 49° High: 77° Low: 47° High: 74° Low: 46° High: 76°
               
NE
6-21
mph
ENE
4-23
mph
E→NW
calm

NW
4-23
mph
NNW
5-17
mph
N→NE
4-23
mph
NE→E
3
mph
ESE
4-23
mph
UV: 5
 Medium 
UV: 5
 Medium 
UV: 5
 Medium 
UV: 5
 Medium 

 

Tonight
 
Fair. Patchy light fog after midnight. Low 51°. Wind northeast around 6 mph, gusting to 21 mph.
Saturday
 
Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 75°. UV index up to 5. Wind east-northeast around 4 mph, gusting to 23 mph.
Saturday night
 
Partly cloudy. Low 49°. Wind east near calm in the evening, becoming northwest after midnight.
Sunday
 
Sunny. Warm. High 77°. UV index up to 5. Wind northwest around 4 mph, gusting to 23 mph.
Sunday night
 
Clear. Low 47°. Wind north-northwest around 5 mph, gusting to 17 mph.
Monday
 
Sunny. High 74°. UV index up to 5. Wind north around 4 mph, gusting to 23 mph, in the morning, becoming northeast in the afternoon.
Monday night
 
Clear. Low 46°. Wind northeast around 3 mph in the evening, becoming east after midnight.
Tuesday
 
Sunny. Warm. High 76°. UV index up to 5. Wind east-southeast around 4 mph, gusting to 23 mph.
Tuesday night
 
Clear in the evening, becoming fair to partly cloudy after midnight. Low 48°. Wind southeast around 4 mph in the evening, becoming south after midnight.
Wednesday
 
Sunny. Warm. High 81°. UV index up to 5. Wind south-southwest around 4 mph, gusting to 22 mph, in the morning, becoming west-southwest in the afternoon.
Wednesday night
 
Clear. Low 49°. Wind north-northwest around 2 mph in the evening, becoming east after midnight.
Thursday
 
Sunny. Warm. High 82°. UV index up to 5. Wind southwest around 5 mph, gusting to 19 mph, in the morning, becoming 9 mph, gusting to 22 mph, in the afternoon.
Thursday night
 
Clear. Low 51°. Wind west around 5 mph in the evening, becoming north after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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