WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Wednesday, 27-May-2026 05:00 am
 
Today

Partly Cloudy
Partly Cloudy
Tonight

Partly Cloudy
Partly Cloudy
Thursday

Mostly Cloudy
Mostly Cloudy
Thursday
night
Mostly Cloudy
Mostly Cloudy
Friday

Thunder storm
Thunder storm
Friday
night
Partly Cloudy
Partly Cloudy
Saturday

Partly Cloudy
Partly Cloudy
Saturday
night
Partly Cloudy
Partly Cloudy
<.1 in.
High: 89° Low: 66° High: 88° Low: 65° High: 84° Low: 62° High: 86° Low: 60°
               
NW→N
1-23→4-23
mph
NE
2-21
mph
ENE
4-24→7-26
mph
ENE
5-22
mph
E
6-24
mph
ESE
3-19
mph
ESE
5-25
mph
E
5-22
mph
UV: 8
 Very High 
UV: 8
 Very High 
UV: 6
 High 
UV: 9
 Very High 

 

Today
 
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Hot. High 89°. UV index up to 8. Wind northwest around 1 mph, gusting to 23 mph, in the morning, becoming north around 4 mph, gusting to 23 mph, in the afternoon.
Tonight
 
Partly cloudy. Low 66°. Wind northeast around 2 mph, gusting to 21 mph.
Thursday
 
Partly to mostly cloudy. Hot. High 88°. UV index up to 8. Wind east-northeast around 4 mph, gusting to 24 mph, in the morning, becoming 7 mph, gusting to 26 mph, in the afternoon.
Thursday night
 
Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Low 65°. Wind east-northeast around 5 mph, gusting to 22 mph.
Friday
 
Mostly cloudy. A slight chance of rain in the afternoon. Scattered thundershowers possible. High 84°. UV index up to 6. Wind east around 6 mph, gusting to 24 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Friday night
 
Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 62°. Wind east-southeast around 3 mph, gusting to 19 mph.
Saturday
 
Partly cloudy in the morning, becoming mostly sunny in the afternoon. Hot. High 86°. UV index up to 9. Wind east-southeast around 5 mph, gusting to 25 mph.
Saturday night
 
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Low 60°. Wind east around 5 mph, gusting to 22 mph.
Sunday
 
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Warm. High 85°. UV index up to 7. Wind east around 6 mph, gusting to 24 mph.
Sunday night
 
Fair to partly cloudy in the evening, becoming clear after midnight. Relatively cool. Low 58°. Wind east around 4 mph, gusting to 23 mph.
Monday
 
Partly to mostly sunny. Warm. High 84°. UV index up to 9. Wind northeast around 5 mph, gusting to 24 mph, in the morning, becoming 9 mph, gusting to 27 mph, in the afternoon.
Monday night
 
Clear. Relatively cool. Low 59°. Wind northeast around 9 mph, gusting to 26 mph.
Tuesday
 
Sunny. Breezy. High 77°. UV index up to 10. Wind northeast around 12 mph, gusting to 30 mph.
Tuesday night
 
Clear. Relatively cool. Low 56°. Wind north-northeast around 7 mph, gusting to 26 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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