WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Tuesday, 24-Mar-2026 04:00 pm
 
Tonight

Partly Cloudy
Partly Cloudy
Wednesday

Mostly Sunny
Mostly Sunny
Wednesday
night
Partly Cloudy
Partly Cloudy
Thursday

Mostly Sunny
Mostly Sunny
Thursday
night
Rain likely
Rain likely
Friday

Mostly Cloudy
Mostly Cloudy
Friday
night
Partly Cloudy
Partly Cloudy
Saturday

Mostly Sunny
Mostly Sunny
.25 in. <.1 in.
Low: 41° High: 77° Low: 52° High: 89° Low: 50° High: 58° Low: 39° High: 62°
               
SE
6-27
mph
S
5-21→8-25
mph
SSW
8-20
mph
SSW
11-29
mph
WSW→NNE
8-19→13-27
mph
NNE
12-30
mph
N
5-26
mph
E→SSE
4-23
mph
UV: 7
 High 
UV: 7
 High 
UV: 7
 High 
UV: 7
 High 

 

Tonight
 
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Low 41°. Wind southeast around 6 mph, gusting to 27 mph.
Wednesday
 
Partly to mostly sunny. Unusually warm. High 77°. UV index up to 7. Wind south around 5 mph, gusting to 21 mph, in the morning, becoming 8 mph, gusting to 25 mph, in the afternoon.
Wednesday night
 
Fair to partly cloudy. Low 52°. Wind south-southwest around 8 mph, gusting to 20 mph.
Thursday
 
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Near record warmth. High 89°. UV index up to 7. Wind south-southwest around 11 mph, gusting to 29 mph.
Thursday night
 
Mostly cloudy in the evening, becoming dense overcast after midnight. A slight chance of rain in the evening, then rain likely after midnight. Precipitation showery or intermittent. Low 50°. Wind west-southwest around 8 mph, gusting to 19 mph, in the evening, becoming north-northeast around 13 mph, gusting to 27 mph, after midnight. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.
Friday
 
Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A chance of rain. Breezy. High 58°. UV index up to 7. Wind north-northeast around 12 mph, gusting to 30 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night
 
Partly cloudy in the evening, becoming clear after midnight. Low 39°. Wind north around 5 mph, gusting to 26 mph.
Saturday
 
Sunny in the morning, becoming partly to mostly sunny in the afternoon. High 62°. UV index up to 7. Wind east around 4 mph, gusting to 23 mph, in the morning, becoming south-southeast in the afternoon.
Saturday night
 
Partly cloudy. Low 40°. Wind south-southeast around 6 mph, gusting to 20 mph.
Sunday
 
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Mild. High 67°. UV index up to 5. Wind south-southeast around 9 mph, gusting to 26 mph.
Sunday night
 
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 47°. Wind south around 10 mph, gusting to 23 mph.
Monday
 
Partly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Breezy and unusually warm. High 78°. UV index up to 5. Wind south-southwest around 12 mph, gusting to 30 mph, in the morning, becoming 17 mph, gusting to 31 mph, in the afternoon.
Monday night
 
Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Breezy and mild. Low 60°. Wind south-southwest around 12 mph, gusting to 26 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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