WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Tuesday, 28-Apr-2026 05:00 am
 
Today

Chance rain
Chance rain
Tonight

Chance rain
Chance rain
Wednesday

Fog a.m.
Fog a.m.
Wednesday
night
Partly Cloudy
Partly Cloudy
Thursday

Mostly Cloudy
Mostly Cloudy
Thursday
night
Chance rain
Chance rain
Friday

Partly Cloudy
Partly Cloudy
Friday
night
Mostly Cloudy
Mostly Cloudy
<.1 in. <.25 in. .1 in.
High: 76° Low: 53° High: 66° Low: 44° High: 66° Low: 46° High: 60° Low: 41°
               
WNW→NE
5-30
mph
NNE
5-18
mph
NNW
9-27
mph
NNW
6-24→3
mph
WNW
2-29→6-26
mph
W→NNW
4-17
mph
N
10-28
mph
N
4-24
mph
UV: 7
 High 
UV: 5
 Medium 
UV: 6
 High 
UV: 7
 High 

 

Today
 
Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. A chance of rain in the afternoon. High 76°. UV index up to 7. Wind west-northwest around 5 mph, gusting to 30 mph, in the morning, becoming northeast in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Tonight
 
Mostly cloudy to cloudy in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Low 53°. Wind north-northeast around 5 mph, gusting to 18 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Wednesday
 
Sunny in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. High 66°. UV index up to 5. Wind north-northwest around 9 mph, gusting to 27 mph.
Wednesday night
 
Partly cloudy in the evening, becoming clear after midnight. Cool. Low 44°. Wind north-northwest around 6 mph, gusting to 24 mph, in the evening, becoming 3 mph after midnight.
Thursday
 
Mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. High 66°. UV index up to 6. Wind west-northwest around 2 mph, gusting to 29 mph, in the morning, becoming 6 mph, gusting to 26 mph, in the afternoon.
Thursday night
 
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. A chance of rain. Cool. Low 46°. Wind west around 4 mph, gusting to 17 mph, in the evening, becoming north-northwest after midnight. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Friday
 
Partly cloudy. Cool. High 60°. UV index up to 7. Wind north around 10 mph, gusting to 28 mph.
Friday night
 
Partly to mostly cloudy in the evening, becoming mostly clear after midnight. Cool. Low 41°. Wind north around 4 mph, gusting to 24 mph.
Saturday
 
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Cool. High 59°. UV index up to 6. Wind north-northwest around 6 mph, gusting to 27 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon.
Saturday night
 
Fair in the evening, becoming clear after midnight. Cool. Low 41°. Wind north-northwest around 4 mph, gusting to 22 mph, in the evening, becoming southwest after midnight.
Sunday
 
Sunny in the morning, becoming partly cloudy in the afternoon. High 68°. UV index up to 6. Wind southwest around 8 mph, gusting to 26 mph.
Sunday night
 
Mostly cloudy in the evening, becoming partly cloudy after midnight. A slight chance of rain. Low 48°. Wind southwest around 5 mph, gusting to 20 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday
 
Partly to mostly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. High 69°. UV index up to 6. Wind west-southwest around 6 mph, gusting to 24 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Monday night
 
Clear. Patchy light fog after midnight. Low 51°. Wind west-southwest around 6 mph, gusting to 17 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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