WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Saturday, 30-May-2026 05:00 am
 
Today

Thunder storm
Thunder storm
Tonight

Chance rain
Chance rain
Sunday

Thunder storm
Thunder storm
Sunday
night
Thunder storm
Thunder storm
Monday

Thunder storm
Thunder storm
Monday
night
Partly Cloudy
Partly Cloudy
Tuesday

Partly Cloudy
Partly Cloudy
Tuesday
night
Partly Cloudy
Partly Cloudy
.1 in. <.1 in. <.1 in. <.1 in. <.1 in.
High: 86° Low: 72° High: 86° Low: 71° High: 86° Low: 66° High: 84° Low: 61°
               
ESE
3-23→7-24
mph
ESE
6-21
mph
ESE
6-25
mph
ESE
4-22
mph
ENE
3-23
mph
NNE
4-18
mph
ENE
6-25
mph
E
8-24→4
mph
UV: 5
 Medium 
UV: 7
 High 
UV: 6
 High 
UV: 9
 Very High 

 

Today
 
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. Hot. High 86°. UV index up to 5. Wind east-southeast around 3 mph, gusting to 23 mph, in the morning, becoming 7 mph, gusting to 24 mph, in the afternoon. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Tonight
 
Mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. A chance of rain. Precipitation showery or intermittent. Low 72°. Wind east-southeast around 6 mph, gusting to 21 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday
 
Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 86°. UV index up to 7. Wind east-southeast around 6 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday night
 
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A slight chance of rain. Scattered thundershowers possible. Low 71°. Wind east-southeast around 4 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday
 
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thunderstorms likely. Hot. High 86°. UV index up to 6. Wind east-northeast around 3 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Monday night
 
Fair to partly cloudy in the evening, becoming mostly cloudy after midnight. Low 66°. Wind north-northeast around 4 mph, gusting to 18 mph.
Tuesday
 
Partly cloudy in the morning, becoming sunny in the afternoon. High 84°. UV index up to 9. Wind east-northeast around 6 mph, gusting to 25 mph.
Tuesday night
 
Partly cloudy. Low 61°. Wind east around 8 mph, gusting to 24 mph, in the evening, becoming 4 mph after midnight.
Wednesday
 
Sunny. High 83°. UV index up to 9. Wind east-southeast around 6 mph, gusting to 25 mph.
Wednesday night
 
Fair. Relatively cool. Low 57°. Wind southeast around 5 mph, gusting to 23 mph.
Thursday
 
Partly to mostly sunny. Hot. High 86°. UV index up to 9. Wind south around 6 mph, gusting to 25 mph.
Thursday night
 
Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 64°. Wind south-southeast around 6 mph, gusting to 22 mph.
Friday
 
Partly to mostly cloudy. Hot. High 90°. UV index up to 8. Wind south-southwest around 8 mph, gusting to 27 mph.
Friday night
 
Mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Patchy light fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Precipitation showery or intermittent. Low 65°. Wind southwest around 6 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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