WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Tuesday, 13-May-2025 04:00 pm
 
Tonight

Fog late
Fog late
Wednesday

Thunder storm
Thunder storm
Wednesday
night
Thunder storm
Thunder storm
Thursday

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

Mostly Sunny
Mostly Sunny
Friday
night
Mostly Clear
Mostly Clear
Saturday

Mostly Sunny
Mostly Sunny
<.1 in. <.1 in.
Low: 59° High: 80° Low: 62° High: 91° Low: 57° High: 89° Low: 59° High: 86°
               
SE
4-22
mph
SE
6-20→10-25
mph
SE
7-22
mph
SSE→SSW
8-26→12-29
mph
SW
9-24→6
mph
SSW
6-25→12-29
mph
SW
9-25→5
mph
WSW
8-28
mph
UV: 8
 Very High 
UV: 8
 Very High 
UV: 10
 Very High 
UV: 8
 Very High 

 

Tonight
 
Mostly clear in the evening, becoming clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 59°. Wind southeast around 4 mph, gusting to 22 mph.
Wednesday
 
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. High 80°. UV index up to 8. Wind southeast around 6 mph, gusting to 20 mph, in the morning, becoming 10 mph, gusting to 25 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night
 
Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Scattered thunderstorms likely. Low 62°. Wind southeast around 7 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Thursday
 
Mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Very hot. High 91°. UV index up to 8. Wind south-southeast around 8 mph, gusting to 26 mph, in the morning, becoming south-southwest around 12 mph, gusting to 29 mph, in the afternoon.
Thursday night
 
Partly cloudy in the evening, becoming clear after midnight. Low 57°. Wind southwest around 9 mph, gusting to 24 mph, in the evening, becoming 6 mph after midnight.
Friday
 
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Unusually hot. High 89°. UV index up to 10. Wind south-southwest around 6 mph, gusting to 25 mph, in the morning, becoming 12 mph, gusting to 29 mph, in the afternoon.
Friday night
 
Mostly clear in the evening, becoming clear after midnight. Low 59°. Wind southwest around 9 mph, gusting to 25 mph, in the evening, becoming 5 mph after midnight.
Saturday
 
Sunny in the morning, becoming partly to mostly sunny in the afternoon. Hot. High 86°. UV index up to 8. Wind west-southwest around 8 mph, gusting to 28 mph.
Saturday night
 
Clear in the evening, becoming fair to partly cloudy after midnight. Low 56°. Wind west-southwest around 3 mph, gusting to 23 mph, in the evening, becoming south-southeast after midnight.
Sunday
 
Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thunderstorms likely. High 81°. UV index up to 8. Wind east-northeast around 6 mph, gusting to 26 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 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. Scattered thunderstorms likely. Low 62°. Wind east-southeast around 6 mph, gusting to 21 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch.
Monday
 
Cloudy in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Rain likely in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. Breezy. High 80°. UV index up to 10. Wind east-southeast around 10 mph, gusting to 24 mph, in the morning, becoming 14 mph, gusting to 31 mph, in the afternoon. Chance of precipitation 80 percent. Precipitation mostly around half an inch.
Monday night
 
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog after midnight. A chance of rain in the evening, then rain likely after midnight. Thunderstorms very likely, some possibly severe. Breezy. Low 69°. Wind east-southeast around 14 mph, gusting to 30 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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