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: Friday, 21-Aug-2026 04:00 pm

Tonight Chance rain	Saturday Fog a.m.	Saturday night Chance rain	Sunday Fog a.m.	Sunday night Fog late	Monday Fog a.m.	Monday night Fog late	Tuesday Chance rain
<.1 in.		<.1 in.	<.1 in.				.1 in.
Low: 72°	High: 88°	Low: 67°	High: 83°	Low: 65°	High: 85°	Low: 63°	High: 84°
	Heat: 92°
SW→W 2-19 mph	NNW 5-23 mph	N 3-17 mph	N 3-21 mph	E 3 mph	E 5-23 mph	E 5-20 mph	ESE 5-20 mph
	UV: 7 High		UV: 7 High		UV: 7 High		UV: 6 High

Tonight	Fair to partly cloudy. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Low 72°. Wind southwest around 2 mph, gusting to 19 mph, in the evening, becoming west after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Mostly sunny. Moderate fog in the morning. Hot. High 88°. Heat index up to 92°. UV index up to 7. Wind north-northwest around 5 mph, gusting to 23 mph.
Saturday night	Fair to partly cloudy. Light to moderate fog after midnight. A chance of rain. Low 67°. Wind north around 3 mph, gusting to 17 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. High 83°. UV index up to 7. Wind north around 3 mph, gusting to 21 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 65°. Wind east around 3 mph.
Monday	Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. High 85°. UV index up to 7. Wind east around 5 mph, gusting to 23 mph.
Monday night	Fair. Patchy light fog after midnight. Low 63°. Wind east around 5 mph, gusting to 20 mph.
Tuesday	Partly cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Precipitation showery or intermittent. High 84°. UV index up to 6. Wind east-southeast around 5 mph, gusting to 20 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Tuesday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Low 67°. Wind east-northeast around 4 mph, gusting to 17 mph, in the evening, becoming southeast after midnight.
Wednesday	Mostly cloudy. High 86°. UV index up to 5. Wind southeast around 2 mph, gusting to 16 mph, in the morning, becoming east-northeast in the afternoon.
Wednesday night	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 66°. Wind east-southeast near calm in the evening, becoming west-southwest after midnight.
Thursday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 86°. UV index up to 7. Wind north-northwest around 4 mph, gusting to 18 mph, in the morning, becoming northeast in the afternoon.
Thursday night	Clear in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 65°. Wind east-northeast around 5 mph, gusting to 16 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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