OFallon Missouri Weather

OFallon - Weather Data from OFallon, MO

Latitude: N 38° 50' 20" Longitude: W 90° 43' 42" Altitude: 532 ft

CDT UTC Last station update CDT

WXSIM Forecast for: O'Fallon
Issued by: OFallonweather.com

Updated: Sunday, 19-Jul-2026 04:00 pm

Tonight Rain likely	Monday Rain likely Hot!	Monday night Chance rain	Tuesday Chance rain	Tuesday night Fog late	Wednesday Fog a.m.	Wednesday night Partly Cloudy	Thursday Partly Cloudy
.1 in.	.1 in.	<.1 in.	<.1 in.
Low: 76°	High: 90°	Low: 76°	High: 90°	Low: 70°	High: 87°	Low: 66°	High: 88°
	Heat: 100°		Heat: 98°
ENE 4-22 mph	SE→SW 3-17 mph	SSW 4 mph	WNW 7-21 mph	N 6-18 mph	N 7-25 mph	NE 5-24 mph	ENE 4-24 mph
	UV: 7 High		UV: 8 Very High		UV: 7 High		UV: 9 Very High

Tonight	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely. Low 76°. Wind east-northeast around 4 mph, gusting to 22 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch.
Monday	Mostly cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely. High 90°. Heat index up to 100°. UV index up to 7. Wind southeast around 3 mph, gusting to 17 mph, in the morning, becoming southwest in the afternoon. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch.
Monday night	Fair to partly cloudy in the evening, becoming fair after midnight. Patchy light fog in the evening, then moderate to dense fog after midnight. A chance of rain. Low 76°. Wind south-southwest around 4 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Precipitation showery or intermittent. High 90°. Heat index up to 98°. UV index up to 8. Wind west-northwest around 7 mph, gusting to 21 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Fair to partly cloudy. Light to moderate fog after midnight. Low 70°. Wind north around 6 mph, gusting to 18 mph.
Wednesday	Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. High 87°. UV index up to 7. Wind north around 7 mph, gusting to 25 mph.
Wednesday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Relatively cool. Low 66°. Wind northeast around 5 mph, gusting to 24 mph.
Thursday	Partly cloudy. High 88°. UV index up to 9. Wind east-northeast around 4 mph, gusting to 24 mph.
Thursday night	Partly cloudy. Relatively cool. Low 66°. Wind east-northeast around 4 mph, gusting to 22 mph.
Friday	Mostly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. A chance of rain. High 85°. UV index up to 6. Wind east around 5 mph, gusting to 24 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Partly to mostly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Relatively cool. Low 66°. Wind east around 4 mph, gusting to 22 mph.
Saturday	Sunny. Patchy light fog in the morning. High 87°. UV index up to 9. Wind east around 7 mph, gusting to 29 mph, in the morning, becoming 10 mph, gusting to 29 mph, in the afternoon.
Saturday night	Mostly clear. Relatively cool. Low 65°. Wind east around 4 mph, gusting to 25 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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