WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Wednesday, 04-Mar-2026 05:00 am
 
Today

Chance rain
Chance rain
Tonight

Rain likely
Rain likely
Thursday

Fog a.m.
Fog a.m.
Thursday
night
Mostly Cloudy
Mostly Cloudy
Friday

Fog a.m.
Fog a.m.
Friday
night
Thunder storm
Thunder storm
Saturday

Fog a.m.
Fog a.m.
Saturday
night
Partly Cloudy
Partly Cloudy
<.25 in. .75 in. .25 in. <.1 in.
High: 58° Low: 49° High: 67° Low: 51° High: 77° Low: 60° High: 67° Low: 40°
               
NE→E
3
mph
E→WSW
3
mph
WSW
6-24
mph
E→SSE
4-19
mph
SSE
9-23→13-28
mph
S
11-20
mph
W
10-29
mph
WNW
4-24
mph
UV: 4
 Medium 
UV: 5
 Medium 

 

Today
 
Cloudy in the morning, becoming dense overcast in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Relatively mild. High 58°. Wind northeast around 3 mph in the morning, becoming east in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Tonight
 
Cloudy. Patchy light fog in the evening, then light to moderate fog after midnight. Rain likely. Relatively mild. Low 49°. Wind east around 3 mph in the evening, becoming west-southwest after midnight. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch.
Thursday
 
Mostly cloudy to cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. Mild. High 67°. Wind west-southwest around 6 mph, gusting to 24 mph.
Thursday night
 
Mostly cloudy in the evening, becoming cloudy after midnight. Relatively mild. Low 51°. Wind east around 4 mph, gusting to 19 mph, in the evening, becoming south-southeast after midnight.
Friday
 
Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. Unusually warm. High 77°. UV index up to 4. Wind south-southeast around 9 mph, gusting to 23 mph, in the morning, becoming 13 mph, gusting to 28 mph, in the afternoon.
Friday night
 
Partly to mostly cloudy in the evening, becoming cloudy after midnight. Rain likely. Scattered thundershowers possible. Breezy and mild. Low 60°. Wind south around 11 mph, gusting to 20 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.
Saturday
 
Mostly cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Precipitation showery or intermittent. Mild. High 67°. UV index up to 5. Wind west around 10 mph, gusting to 29 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night
 
Partly cloudy. Low 40°. Wind west-northwest around 4 mph, gusting to 24 mph.
Sunday
 
Partly cloudy. Mild. High 65°. Wind south-southwest around 5 mph, gusting to 23 mph.
Sunday night
 
Mostly clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 42°. Wind south-southwest around 5 mph, gusting to 17 mph.
Monday
 
Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the afternoon. Unusually warm. High 70°. Wind south-southwest around 7 mph, gusting to 20 mph, in the morning, becoming 12 mph, gusting to 25 mph, in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday night
 
Mostly cloudy to cloudy in the evening, becoming dense overcast after midnight. Patchy light fog. A chance of rain in the evening, then rain likely after midnight. Precipitation showery or intermittent. Relatively mild. Low 56°. Wind south-southwest around 9 mph, gusting to 19 mph. Chance of precipitation 80 percent. Precipitation mostly around half an inch.
Tuesday
 
Dense overcast. Patchy light fog. Rain very likely. Precipitation showery or intermittent. Breezy and mild. High 63°. Wind south-southwest around 12 mph, gusting to 21 mph, in the morning, becoming 15 mph, gusting to 25 mph, in the afternoon. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch.
Tuesday night
 
Dense overcast. Light to moderate fog. Rain likely. Scattered thundershowers possible. Relatively mild. Low 52°. Wind south-southwest around 10 mph, gusting to 24 mph, in the evening, becoming west after midnight. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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