WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Saturday, 28-Mar-2026 04:00 pm
 
Tonight

Partly Cloudy
Partly Cloudy
Sunday

Mostly Cloudy
Mostly Cloudy
Sunday
night
Partly Cloudy
Partly Cloudy
Monday

Mostly Sunny
Mostly Sunny
Monday
night
Partly Cloudy
Partly Cloudy
Tuesday

Thunder storm
Thunder storm
Tuesday
night
Thunder storm
Thunder storm
Wednesday

Chance rain
Chance rain
<.25 in. 1.0 in. <.25 in.
Low: 39° High: 70° Low: 42° High: 85° Low: 59° High: 88° Low: 52° High: 54°
               
SSE
7-26
mph
SSE
8-27
mph
SSE
8-22
mph
S
11-29
mph
S
11-22
mph
SSW
12-30
mph
NNW
9-25
mph
NNE
8-25
mph
UV: 6
 High 
UV: 7
 High 
UV: 6
 High 

 

Tonight
 
Fair in the evening, becoming partly cloudy after midnight. Low 39°. Wind south-southeast around 7 mph, gusting to 26 mph.
Sunday
 
Partly to mostly cloudy. Mild. High 70°. UV index up to 6. Wind south-southeast around 8 mph, gusting to 27 mph.
Sunday night
 
Fair to partly cloudy in the evening, becoming clear after midnight. Low 42°. Wind south-southeast around 8 mph, gusting to 22 mph.
Monday
 
Sunny in the morning, becoming mostly sunny in the afternoon. Unusually hot. High 85°. UV index up to 7. Wind south around 11 mph, gusting to 29 mph.
Monday night
 
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Mild. Low 59°. Wind south around 11 mph, gusting to 22 mph.
Tuesday
 
Partly to mostly cloudy. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. Breezy and exceptionally hot. High 88°. UV index up to 6. Wind south-southwest around 12 mph, gusting to 30 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Tuesday night
 
Dense overcast. Patchy light fog. Rain likely. Scattered thunderstorms likely. Low 52°. Wind north-northwest around 9 mph, gusting to 25 mph. Chance of precipitation 80 percent. Precipitation mostly around an inch.
Wednesday
 
Dense overcast. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 54°. Wind north-northeast around 8 mph, gusting to 25 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Wednesday night
 
Dense overcast. Patchy light fog after midnight. A chance of rain in the evening, then rain likely after midnight. Low 44°. Wind east-northeast around 7 mph, gusting to 21 mph. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch.
Thursday
 
Dense overcast. Patchy light fog in the morning. Rain likely in the morning, then a chance of rain in the afternoon. High 48°. Wind east-northeast around 7 mph. Chance of precipitation 80 percent. Precipitation mostly around half an inch.
Thursday night
 
Dense overcast in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Rain likely in the evening, then a chance of rain after midnight. Low 44°. Wind north-northeast around 4 mph. Chance of precipitation 80 percent. Precipitation mostly around an inch.
Friday
 
Mostly cloudy. Patchy light fog in the morning. Mild. High 70°. UV index up to 6. Wind southeast around 5 mph, gusting to 19 mph, in the morning, becoming 9 mph, gusting to 25 mph, in the afternoon.
Friday night
 
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog after midnight. A chance of rain after midnight. Precipitation showery or intermittent. Low 56°. Wind south-southeast around 9 mph, gusting to 20 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.

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