WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Wednesday, 25-Mar-2026 05:00 am
 
Today

Mostly Sunny
Mostly Sunny
Tonight

Partly Cloudy
Partly Cloudy
Thursday

Mostly Sunny
Mostly Sunny
Thursday
night
Thunder storm
Thunder storm
Friday

Mostly Cloudy
Mostly Cloudy
Friday
night
Clear
Clear
Saturday

Mostly Sunny
Mostly Sunny
Saturday
night
Partly Cloudy
Partly Cloudy
.1 in. <.1 in.
High: 79° Low: 53° High: 93° Low: 55° High: 61° Low: 37° High: 62° Low: 41°
               
SSE
4-24→8-26
mph
S→SW
9-21
mph
SW
11-30
mph
SW→N
10-29
mph
N
12-31
mph
N
6-27
mph
ENE→SE
6-26
mph
SSE
7-24
mph
UV: 7
 High 
UV: 7
 High 
UV: 6
 High 
UV: 6
 High 

 

Today
 
Partly to mostly sunny. Unusually warm. High 79°. UV index up to 7. Wind south-southeast around 4 mph, gusting to 24 mph, in the morning, becoming 8 mph, gusting to 26 mph, in the afternoon.
Tonight
 
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Low 53°. Wind south around 9 mph, gusting to 21 mph, in the evening, becoming southwest after midnight.
Thursday
 
Partly to mostly sunny. Breezy with near record heat. High 93°. UV index up to 7. Wind southwest around 11 mph, gusting to 30 mph.
Thursday night
 
Partly cloudy in the evening, becoming cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Mild. Low 55°. Wind southwest around 10 mph, gusting to 29 mph, in the evening, becoming north after midnight. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Friday
 
Mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A slight chance of rain in the morning. Breezy. High 61°. UV index up to 6. Wind north around 12 mph, gusting to 31 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night
 
Clear. Low 37°. Wind north around 6 mph, gusting to 27 mph.
Saturday
 
Sunny in the morning, becoming mostly sunny in the afternoon. High 62°. UV index up to 6. Wind east-northeast around 6 mph, gusting to 26 mph, in the morning, becoming southeast in the afternoon.
Saturday night
 
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 41°. Wind south-southeast around 7 mph, gusting to 24 mph.
Sunday
 
Partly cloudy. Mild. High 71°. UV index up to 6. Wind south-southeast around 8 mph, gusting to 26 mph.
Sunday night
 
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Low 45°. Wind south around 10 mph, gusting to 22 mph.
Monday
 
Partly cloudy. A slight chance of rain. Unusually hot. High 82°. UV index up to 6. Wind south-southwest around 10 mph, gusting to 27 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday night
 
Mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Mild. Low 60°. Wind south-southwest around 10 mph, gusting to 19 mph.
Tuesday
 
Cloudy in the morning, becoming mostly cloudy in the afternoon. Breezy and unusually hot. High 83°. UV index up to 5. Wind south-southwest around 14 mph, gusting to 32 mph.
Tuesday night
 
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Breezy and mild. Low 62°. Wind south-southwest around 15 mph, gusting to 30 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

Powered by Davis Vantage Pro2  and   CumulusMX   v 4.6.4 (b4128)   MXUI Template v 2.2.6 by  Silver Acorn     Valid HTML5 USA Weather Finder Badge