WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com
Updated: Tuesday, 27-Oct-2026 04:00 pm
 
Tonight

Fog late
Fog late
Wednesday

Fog a.m.
Fog a.m.
Wednesday
night
Fog late
Fog late
Thursday

Fog a.m.
Fog a.m.
Thursday
night
Fog
Fog
Friday

Fog a.m.
Fog a.m.
Friday
night
Mostly Cloudy
Mostly Cloudy
Saturday

Mostly Cloudy
Mostly Cloudy
<.1 in. <.1 in.
Low: 51° High: 76° Low: 51° High: 77° Low: 53° High: 70° Low: 57° High: 72°
               
S
5-19
mph
S
6-23
mph
S
6
mph
SSW→W
5-21
mph
N→NE
3
mph
ESE
5-16
mph
SE
4
mph
E
3-18
mph

 

Tonight
 
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. Low 51°. Wind south around 5 mph, gusting to 19 mph.
Wednesday
 
Mostly sunny. Moderate fog in the morning. Unusually warm. High 76°. Wind south around 6 mph, gusting to 23 mph.
Wednesday night
 
Fair. Light to moderate fog after midnight. Low 51°. Wind south around 6 mph.
Thursday
 
Partly to mostly sunny. Light to moderate fog in the morning. Unusually warm. High 77°. Wind south-southwest around 5 mph, gusting to 21 mph, in the morning, becoming west in the afternoon.
Thursday night
 
Partly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog. A chance of rain. Low 53°. Wind north around 3 mph in the evening, becoming northeast after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday
 
Partly to mostly cloudy in the morning, becoming cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Mild. High 70°. Wind east-southeast around 5 mph, gusting to 16 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night
 
Mostly cloudy in the evening, becoming cloudy after midnight. Mild. Low 57°. Wind southeast around 4 mph.
Saturday
 
Cloudy in the morning, becoming mostly cloudy in the afternoon. Mild. High 72°. Wind east around 3 mph, gusting to 18 mph.
Saturday night
 
Mostly cloudy to cloudy. Mild. Low 56°. Wind east-southeast around 4 mph.
Sunday
 
Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Warm. High 73°. Wind southeast around 4 mph, gusting to 22 mph.
Sunday night
 
Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Mild. Low 58°. Wind southeast around 4 mph, gusting to 18 mph.
Monday
 
Mostly cloudy to cloudy. A slight chance of rain. Mild. High 72°. Wind south-southeast around 3 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday night
 
Dense overcast. Patchy light fog after midnight. A chance of rain in the evening, then rain likely after midnight. Mild. Low 61°. Wind east-southeast around 6 mph, gusting to 19 mph, in the evening, becoming 10 mph, gusting to 22 mph, after midnight. Chance of precipitation 80 percent. Precipitation mostly around an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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