WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Wednesday, 11-Mar-2026 05:00 am
 
Today

Thunder storm
Thunder storm
Tonight

Partly Cloudy
Partly Cloudy
Thursday

Mostly Sunny
Mostly Sunny
Thursday
night
Partly Cloudy
Partly Cloudy
Friday

Partly Cloudy
Partly Cloudy
Friday
night
Partly Cloudy
Partly Cloudy
Saturday

Partly Cloudy
Partly Cloudy
Saturday
night
Partly Cloudy
Partly Cloudy
.35 in.
High: 58° Low: 35° High: 55° Low: 40° High: 57° Low: 34° High: 60° Low: 44°
               
NW
9-24→14-32
mph
NW
12-30→7-25
mph
WSW
4-24→9-26
mph
SSW
12-23→15-23
mph
WNW
11-28
mph
NNW→NE
4-22
mph
ENE→ESE
7-26→11-29
mph
SE
9-25
mph
UV: 5
 Medium 

 

Today
 
Dense overcast in the morning, becoming mostly cloudy to cloudy in the afternoon. Patchy light fog in the morning. Rain likely in the morning, then a slight chance of rain in the afternoon. Thunderstorms very likely, some severe. Breezy. High 58°, but temperatures falling in the afternoon. Wind northwest around 9 mph, gusting to 24 mph, in the morning, becoming 14 mph, gusting to 32 mph, in the afternoon. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch.
Tonight
 
Partly cloudy in the evening, becoming fair after midnight. Low 35°. Wind northwest around 12 mph, gusting to 30 mph, in the evening, becoming 7 mph, gusting to 25 mph, after midnight.
Thursday
 
Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. High 55°. Wind west-southwest around 4 mph, gusting to 24 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon.
Thursday night
 
Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Breezy. Low 40°. Wind south-southwest around 12 mph, gusting to 23 mph, in the evening, becoming 15 mph, gusting to 23 mph, after midnight.
Friday
 
Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Breezy. High 57°. Wind west-northwest around 11 mph, gusting to 28 mph.
Friday night
 
Mostly cloudy in the evening, becoming fair to partly cloudy after midnight. Low 34°. Wind north-northwest around 4 mph, gusting to 22 mph, in the evening, becoming northeast after midnight.
Saturday
 
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. High 60°. UV index up to 5. Wind east-northeast around 7 mph, gusting to 26 mph, in the morning, becoming east-southeast around 11 mph, gusting to 29 mph, in the afternoon.
Saturday night
 
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 44°. Wind southeast around 9 mph, gusting to 25 mph.
Sunday
 
Mostly cloudy to cloudy in the morning, becoming cloudy in the afternoon. A slight chance of rain in the morning, then rain likely in the afternoon. Breezy and mild. High 65°. Wind south around 11 mph, gusting to 25 mph, in the morning, becoming west around 16 mph, gusting to 32 mph, in the afternoon. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch.
Sunday night
 
Mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Windy and cold. Low 29°. Wind chill ranging from 21 to 43. Wind west-northwest around 17 mph, gusting to 33 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Monday
 
Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Breezy and cold. High 35°. Wind chill ranging from 19 to 26. Wind west-northwest around 13 mph, gusting to 30 mph.
Monday night
 
Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Cold. Low 27°. Wind north-northwest around 7 mph, gusting to 24 mph, in the evening, becoming east around 4 mph, gusting to 16 mph, after midnight.
Tuesday
 
Cloudy in the morning, becoming dense overcast in the afternoon. A slight chance of a mix of snow, sleet, and rain in the afternoon. Cold. High 41°. Wind chill ranging from 22 to 33. Wind southeast around 9 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation (liquid equivalent) mostly less than a tenth of an inch. Little or no snow or ice (on ground) accumulation expected.
Tuesday night
 
Dense overcast. A chance of a mix of sleet and rain in the evening, then a slight chance of rain after midnight. Breezy. Low 36°, but temperatures rising after midnight. Wind chill as low as 28. Wind south-southeast around 12 mph, gusting to 24 mph. Chance of precipitation 50 percent. Precipitation (liquid equivalent) mostly around a tenth of an inch. No ice (on ground) accumulation expected.

WXSIM forecast formatting script by Saratoga-Weather.org.

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