WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Wednesday, 26-Aug-2026 05:00 am
 
Today

Mostly Sunny
Mostly Sunny
Tonight

Clear
Clear
Thursday

Mostly Sunny
Mostly Sunny
Thursday
night
Clear
Clear
Friday

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

Mostly Sunny
Mostly Sunny
Saturday
night
Partly Cloudy
Partly Cloudy
High: 94° Low: 67° High: 86° Low: 63° High: 86° Low: 61° High: 90° Low: 64°
Heat: 99°              
SW→WNW
4-24
mph
NNW
3-21
mph
NNW
4-23
mph
NE
2-17
mph
NNE
3-22
mph
E
3-16
mph
SSE
4-22
mph
SSE
6-17
mph
UV: 8
 Very High 
UV: 7
 High 
UV: 7
 High 
UV: 7
 High 

 

Today
 
Mostly sunny in the morning, becoming sunny in the afternoon. Very hot. High 94°. Heat index up to 99°. UV index up to 8. Wind southwest around 4 mph, gusting to 24 mph, in the morning, becoming west-northwest in the afternoon.
Tonight
 
Clear. Low 67°. Wind north-northwest around 3 mph, gusting to 21 mph.
Thursday
 
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Hot. High 86°. UV index up to 7. Wind north-northwest around 4 mph, gusting to 23 mph.
Thursday night
 
Clear. Low 63°. Wind northeast around 2 mph, gusting to 17 mph.
Friday
 
Sunny. Patchy light fog in the morning. High 86°. UV index up to 7. Wind north-northeast around 3 mph, gusting to 22 mph.
Friday night
 
Fair to partly cloudy in the evening, becoming fair after midnight. Low 61°. Wind east around 3 mph, gusting to 16 mph.
Saturday
 
Partly to mostly sunny. Hot. High 90°. UV index up to 7. Wind south-southeast around 4 mph, gusting to 22 mph.
Saturday night
 
Fair in the evening, becoming partly cloudy after midnight. Low 64°. Wind south-southeast around 6 mph, gusting to 17 mph.
Sunday
 
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Very hot. High 94°. UV index up to 7. Wind south around 8 mph, gusting to 24 mph.
Sunday night
 
Fair in the evening, becoming partly cloudy after midnight. Low 68°. Wind south around 8 mph, gusting to 19 mph.
Monday
 
Mostly sunny in the morning, becoming sunny in the afternoon. Very hot. High 97°. Heat index up to 101°. UV index up to 8. Wind south around 8 mph, gusting to 25 mph.
Monday night
 
Clear. Low 68°. Wind south-southwest around 7 mph, gusting to 18 mph.
Tuesday
 
Sunny. Very hot. High 97°. Heat index up to 102°. UV index up to 8. Wind south-southwest around 10 mph, gusting to 26 mph.
Tuesday night
 
Partly cloudy in the evening, becoming clear after midnight. Low 70°. Wind south-southwest around 7 mph, gusting to 18 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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