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, 24-Jul-2026 04:00 pm

Tonight Chance rain	Saturday Thunder storm	Saturday night Chance rain	Sunday Fog a.m. Hot!	Sunday night Fog late	Monday Fog a.m. Hot!	Monday night Clear	Tuesday Partly Cloudy Hot!
<.25 in.	.1 in.	.1 in.	<.1 in.
Low: 67°	High: 89°	Low: 72°	High: 94°	Low: 74°	High: 97°	Low: 73°	High: 97°
	Heat: 95°		Heat: 104°		Heat: 108°		Heat: 103°
S 5-20 mph	S 4-22 mph	ESE→S 2 mph	SW 3-19 mph	SSW 3 mph	SW 6-21→10-25 mph	WSW→NW 5-17 mph	NW 6-24 mph
	UV: 8 Very High		UV: 9 Very High		UV: 9 Very High		UV: 9 Very High

Tonight	Mostly cloudy to cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Precipitation showery or intermittent. Relatively cool. Low 67°. Wind south around 5 mph, gusting to 20 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Saturday	Mostly cloudy to cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thundershowers possible. High 89°. Heat index up to 95°. UV index up to 8. Wind south around 4 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Saturday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Low 72°. Wind east-southeast around 2 mph in the evening, becoming south after midnight. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Sunday	Partly to mostly sunny. Light to moderate fog in the morning. A chance of rain. Hot. High 94°. Heat index up to 104°. UV index up to 9. Wind southwest around 3 mph, gusting to 19 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Mostly clear in the evening, becoming partly to mostly cloudy after midnight. Patchy light fog after midnight. Low 74°. Wind south-southwest around 3 mph.
Monday	Sunny. Patchy light fog in the morning. Very hot. High 97°. Heat index up to 108°. UV index up to 9. Wind southwest around 6 mph, gusting to 21 mph, in the morning, becoming 10 mph, gusting to 25 mph, in the afternoon.
Monday night	Clear. Low 73°. Wind west-southwest around 5 mph, gusting to 17 mph, in the evening, becoming northwest after midnight.
Tuesday	Sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 97°. Heat index up to 103°. UV index up to 9. Wind northwest around 6 mph, gusting to 24 mph.
Tuesday night	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Low 70°. Wind northeast around 4 mph, gusting to 21 mph, in the evening, becoming east after midnight.
Wednesday	Sunny. Hot. High 93°. Heat index up to 98°. UV index up to 9. Wind east-northeast around 3 mph, gusting to 21 mph.
Wednesday night	Clear in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Relatively cool. Low 67°. Wind east-northeast around 3 mph, gusting to 16 mph, in the evening, becoming southeast after midnight.
Thursday	Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 92°. UV index up to 8. Wind east-southeast around 5 mph, gusting to 24 mph.
Thursday night	Partly cloudy in the evening, becoming clear after midnight. Relatively cool. Low 66°. Wind east around 4 mph, gusting to 22 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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