WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Thursday, 08-Oct-2026 05:00 am
 
Today

Sunny
Sunny
Tonight

Partly Cloudy
Partly Cloudy
Friday

Sunny
Sunny
Friday
night
Clear
Clear
Saturday

Partly Cloudy
Partly Cloudy
Saturday
night
Mostly Cloudy
Mostly Cloudy
Sunday

Mostly Cloudy
Mostly Cloudy
Sunday
night
Fog late
Fog late
<.1 in.
High: 81° Low: 52° High: 86° Low: 56° High: 87° Low: 61° High: 81° Low: 54°
               
SE
2-19
mph
SSE
3
mph
S
6-23
mph
S
5
mph
S
3-18→6-24
mph
SE→E
4-18
mph
NE→NNW
3-23
mph
ENE→S
2
mph
UV: 5
 Medium 
UV: 5
 Medium 
UV: 5
 Medium 
UV: 5
 Medium 

 

Today
 
Sunny. Warm. High 81°. UV index up to 5. Wind southeast around 2 mph, gusting to 19 mph.
Tonight
 
Clear in the evening, becoming fair to partly cloudy after midnight. Low 52°. Wind south-southeast around 3 mph.
Friday
 
Sunny. Unusually hot. High 86°. UV index up to 5. Wind south around 6 mph, gusting to 23 mph.
Friday night
 
Clear. Low 56°. Wind south around 5 mph.
Saturday
 
Partly cloudy. Unusually hot. High 87°. UV index up to 5. Wind south around 3 mph, gusting to 18 mph, in the morning, becoming 6 mph, gusting to 24 mph, in the afternoon.
Saturday night
 
Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. A slight chance of rain. Mild. Low 61°. Wind southeast around 4 mph, gusting to 18 mph, in the evening, becoming east after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Sunday
 
Partly to mostly cloudy in the morning, becoming sunny in the afternoon. Warm. High 81°. UV index up to 5. Wind northeast around 3 mph, gusting to 23 mph, in the morning, becoming north-northwest in the afternoon.
Sunday night
 
Clear. Patchy light fog after midnight. Low 54°. Wind east-northeast around 2 mph in the evening, becoming south after midnight.
Monday
 
Sunny. Patchy light fog in the morning. Unusually hot. High 86°. UV index up to 5. Wind south around 5 mph, gusting to 17 mph, in the morning, becoming 8 mph, gusting to 21 mph, in the afternoon.
Monday night
 
Clear in the evening, becoming fair after midnight. Low 61°. Wind south-southwest around 7 mph.
Tuesday
 
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Unusually hot. High 85°. UV index up to 4. Wind northwest around 6 mph, gusting to 25 mph.
Tuesday night
 
Fair to partly cloudy in the evening, becoming clear after midnight. Low 52°. Wind north around 5 mph, gusting to 20 mph, in the evening, becoming east-northeast after midnight.
Wednesday
 
Sunny. Unusually hot. High 83°. UV index up to 4. Wind east-southeast around 7 mph, gusting to 23 mph, in the morning, becoming south-southeast around 10 mph, gusting to 28 mph, in the afternoon.
Wednesday night
 
Clear. Low 53°. Wind south-southeast around 10 mph, gusting to 19 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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