WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Sunday, 20-Sep-2026 05:00 am
 
Today

Partly Cloudy
Partly Cloudy
Tonight

Chance rain
Chance rain
Monday

Chance rain
Chance rain
Monday
night
Cloudy
Cloudy
Tuesday

Partly Cloudy
Partly Cloudy
Tuesday
night
Fog late
Fog late
Wednesday

Fog a.m.
Fog a.m.
Wednesday
night
Partly Cloudy
Partly Cloudy
.1 in. .1 in. <.1 in.
High: 93° Low: 68° High: 75° Low: 63° High: 74° Low: 54° High: 73° Low: 52°
               
NW
3-23
mph
N
3-19
mph
N
4-22
mph
NNE
5-22
mph
NNE
7-25
mph
NNE
6-24
mph
NNE
7-24
mph
NNE
4-20
mph
UV: 6
 High 
UV: 6
 High 
UV: 5
 Medium 

 

Today
 
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Very hot. High 93°. UV index up to 6. Wind northwest around 3 mph, gusting to 23 mph.
Tonight
 
Mostly cloudy in the evening, becoming cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Warm. Low 68°. Wind north around 3 mph, gusting to 19 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Monday
 
Cloudy. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 75°. Wind north around 4 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Monday night
 
Cloudy. Low 63°. Wind north-northeast around 5 mph, gusting to 22 mph.
Tuesday
 
Mostly cloudy to cloudy in the morning, becoming partly cloudy in the afternoon. A slight chance of rain. High 74°. UV index up to 6. Wind north-northeast around 7 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night
 
Fair to partly cloudy. Patchy light fog after midnight. Low 54°. Wind north-northeast around 6 mph, gusting to 24 mph.
Wednesday
 
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 73°. UV index up to 5. Wind north-northeast around 7 mph, gusting to 24 mph.
Wednesday night
 
Fair to partly cloudy. Low 52°. Wind north-northeast around 4 mph, gusting to 20 mph.
Thursday
 
Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. High 74°. UV index up to 5. Wind north-northeast around 5 mph, gusting to 23 mph.
Thursday night
 
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 56°. Wind northeast around 4 mph, gusting to 17 mph.
Friday
 
Dense overcast. A slight chance of rain. High 69°. Wind east-northeast around 4 mph, gusting to 17 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Friday night
 
Cloudy in the evening, becoming dense overcast after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Low 58°. Wind northeast around 5 mph, gusting to 16 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday
 
Dense overcast. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 64°. Wind east around 4 mph, gusting to 16 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Saturday night
 
Dense overcast. A chance of rain in the evening, then a slight chance of rain after midnight. Low 60°. Wind east around 4 mph, gusting to 16 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth 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