WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Saturday, 18-Apr-2026 05:00 am
 
Today

Mostly Cloudy
Mostly Cloudy
Tonight

Clear
Clear
Sunday

Sunny
Sunny
Sunday
night
Mostly Clear
Mostly Clear
Monday

Sunny
Sunny
Monday
night
Partly Cloudy
Partly Cloudy
Tuesday

Mostly Sunny
Mostly Sunny
Tuesday
night
Partly Cloudy
Partly Cloudy
High: 60° Low: 40° High: 64° Low: 39° High: 65° Low: 44° High: 75° Low: 47°
               
NW
13-32
mph
NW→WSW
9-28→5
mph
W
8-28→14-31
mph
N→NE
5-24
mph
ESE
7-26
mph
ESE→S
7-22
mph
S→SW
9-30→14-30
mph
SW
8-24
mph
UV: 7
 High 
UV: 6
 High 
UV: 6
 High 
UV: 6
 High 

 

Today
 
Partly to mostly cloudy in the morning, becoming sunny in the afternoon. Breezy. High 60°. UV index up to 7. Wind northwest around 13 mph, gusting to 32 mph.
Tonight
 
Clear. Cool. Low 40°. Wind northwest around 9 mph, gusting to 28 mph, in the evening, becoming west-southwest around 5 mph after midnight.
Sunday
 
Sunny. Breezy. High 64°. UV index up to 6. Wind west around 8 mph, gusting to 28 mph, in the morning, becoming 14 mph, gusting to 31 mph, in the afternoon.
Sunday night
 
Mostly clear in the evening, becoming clear after midnight. Cool. Low 39°. Wind north around 5 mph, gusting to 24 mph, in the evening, becoming northeast after midnight.
Monday
 
Sunny. High 65°. UV index up to 6. Wind east-southeast around 7 mph, gusting to 26 mph.
Monday night
 
Fair in the evening, becoming fair to partly cloudy after midnight. Cool. Low 44°. Wind east-southeast around 7 mph, gusting to 22 mph, in the evening, becoming south after midnight.
Tuesday
 
Partly to mostly sunny. Breezy and warm. High 75°. UV index up to 6. Wind south around 9 mph, gusting to 30 mph, in the morning, becoming southwest around 14 mph, gusting to 30 mph, in the afternoon.
Tuesday night
 
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Low 47°. Wind southwest around 8 mph, gusting to 24 mph.
Wednesday
 
Sunny in the morning, becoming partly cloudy in the afternoon. Warm. High 76°. UV index up to 6. Wind southwest around 8 mph, gusting to 26 mph.
Wednesday night
 
Clear in the evening, becoming fair after midnight. Low 49°. Wind south around 5 mph, gusting to 18 mph.
Thursday
 
Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Breezy and warm. High 78°. UV index up to 7. Wind south around 9 mph, gusting to 27 mph, in the morning, becoming 16 mph, gusting to 32 mph, in the afternoon.
Thursday night
 
Mostly cloudy to cloudy. Low 59°. Wind south around 10 mph, gusting to 26 mph.
Friday
 
Dense overcast in the morning, becoming mostly cloudy to cloudy in the afternoon. Patchy light fog in the afternoon. Rain very likely. Scattered thunderstorms likely. High 66°. UV index up to 5. Wind south-southwest around 9 mph, gusting to 22 mph. Chance of precipitation 80 percent. Precipitation mostly around an inch.
Friday night
 
Partly cloudy in the evening, becoming clear after midnight. Light to moderate fog in the evening, then patchy light fog after midnight. A chance of rain. Scattered thunderstorms likely. Low 53°. Wind west-northwest around 7 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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