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: Monday, 10-Aug-2026 04:00 pm

Tonight Thunder storm	Tuesday Thunder storm Hot!	Tuesday night Thunder storm	Wednesday Thunder storm Hot!	Wednesday night Thunder storm	Thursday Mostly Sunny Hot!	Thursday night Thunder storm	Friday Fog a.m. Hot!
<.1 in.	<.1 in.	<.1 in.	<.1 in.	<.1 in.		<.1 in.
Low: 77°	High: 93°	Low: 75°	High: 93°	Low: 75°	High: 98°	Low: 75°	High: 94°
	Heat: 104°		Heat: 104°		Heat: 108°		Heat: 103°
S 6-19 mph	SW 7-23 mph	SW→SE 4 mph	WSW 6-22 mph	SSW→SSE 4-17 mph	SSE→WSW 4-21 mph	NE 4-15 mph	E 5-23 mph
	UV: 7 High		UV: 8 Very High		UV: 9 Very High		UV: 8 Very High

Tonight	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely. Thunderstorms very likely, some possibly severe. Low 77°. Wind south around 6 mph, gusting to 19 mph. Chance of precipitation 60 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Partly cloudy. Light to moderate fog in the morning. A chance of rain. Scattered thunderstorms likely. Hot. High 93°. Heat index up to 104°. UV index up to 7. Wind southwest around 7 mph, gusting to 23 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. A chance of rain after midnight. Scattered thundershowers possible. Low 75°. Wind southwest around 4 mph in the evening, becoming southeast after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Partly cloudy. Light to moderate fog in the morning. Rain likely. Scattered thunderstorms likely. Hot. High 93°. Heat index up to 104°. UV index up to 8. Wind west-southwest around 6 mph, gusting to 22 mph. Chance of precipitation 60 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. A chance of rain. Scattered thundershowers possible. Low 75°. Wind south-southwest around 4 mph, gusting to 17 mph, in the evening, becoming south-southeast after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Thursday	Partly to mostly sunny. Very hot. High 98°. Heat index up to 108°. UV index up to 9. Wind south-southeast around 4 mph, gusting to 21 mph, in the morning, becoming west-southwest in the afternoon.
Thursday night	Partly to mostly cloudy. Patchy light fog after midnight. Rain likely. Scattered thunderstorms likely. Low 75°. Wind northeast around 4 mph, gusting to 15 mph. Chance of precipitation 60 percent. Precipitation mostly less than a tenth of an inch.
Friday	Partly cloudy. Patchy light fog in the morning. Hot. High 94°. Heat index up to 103°. UV index up to 8. Wind east around 5 mph, gusting to 23 mph.
Friday night	Fair to partly cloudy. Patchy light fog after midnight. Low 74°. Wind east-southeast around 6 mph, gusting to 21 mph.
Saturday	Sunny. Patchy light fog in the morning. Very hot. High 98°. Heat index up to 108°. UV index up to 8. Wind south-southwest around 5 mph, gusting to 23 mph.
Saturday night	Clear. Low 73°. Wind southeast around 4 mph in the evening, becoming south-southwest after midnight.
Sunday	Sunny. Very hot. High 95°. Heat index up to 102°. UV index up to 8. Wind west-southwest around 11 mph, gusting to 24 mph.
Sunday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Low 70°. Wind north around 6 mph, gusting to 16 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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