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: Thursday, 13-Aug-2026 04:00 pm

Tonight Partly Cloudy	Friday Chance rain Hot!	Friday night Fog late	Saturday Fog a.m. Hot!	Saturday night Fair	Sunday Partly Cloudy Hot!	Sunday night Chance rain	Monday Fog a.m.
<.1 in.	<.1 in.	<.1 in.	<.1 in.			.1 in.
Low: 80°	High: 100°	Low: 77°	High: 97°	Low: 77°	High: 97°	Low: 73°	High: 90°
	Heat: 117°		Heat: 111°		Heat: 109°		Heat: 95°
SSW 5-26 mph	SW 3-23 mph	SE→SSW 4-16 mph	SW 6-20 mph	SW 3 mph	WSW 5-24 mph	N 5-18 mph	N 5-24 mph
	UV: 8 Very High		UV: 7 High		UV: 7 High		UV: 8 Very High

Tonight	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. A chance of rain. Warm. Low 80°. Wind south-southwest around 5 mph, gusting to 26 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday	Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A chance of rain. Precipitation showery or intermittent. Very hot. High 100°. Heat index up to 117°. UV index up to 8. Wind southwest around 3 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Fair to partly cloudy. Patchy light fog after midnight. A chance of rain. Warm. Low 77°. Wind southeast around 4 mph, gusting to 16 mph, in the evening, becoming south-southwest after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Very hot. High 97°. Heat index up to 111°. UV index up to 7. Wind southwest around 6 mph, gusting to 20 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Fair. Warm. Low 77°. Wind southwest around 3 mph.
Sunday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 97°. Heat index up to 109°. UV index up to 7. Wind west-southwest around 5 mph, gusting to 24 mph.
Sunday night	Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Precipitation showery or intermittent. Low 73°. Wind north around 5 mph, gusting to 18 mph. Chance of precipitation 40 percent. Precipitation mostly around 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. Hot. High 90°. Heat index up to 95°. UV index up to 8. Wind north around 5 mph, gusting to 24 mph.
Monday night	Fair to partly cloudy in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 67°. Wind north-northeast around 3 mph, gusting to 21 mph.
Tuesday	Sunny. Patchy light fog in the morning. Hot. High 90°. Heat index up to 95°. UV index up to 8. Wind northeast around 3 mph, gusting to 22 mph.
Tuesday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Moderate fog after midnight. A chance of rain. Low 69°. Wind east-southeast around 4 mph, gusting to 16 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Partly cloudy. Patchy light fog in the morning. Hot. High 94°. Heat index up to 100°. UV index up to 6. Wind southeast around 6 mph, gusting to 24 mph, in the morning, becoming northeast in the afternoon.
Wednesday night	Partly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Low 72°. Wind northeast around 5 mph, gusting to 18 mph, in the evening, becoming east-southeast after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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