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, 26-Jul-2026 04:00 pm

Tonight Thunder storm	Monday Thunder storm Hot!	Monday night Thunder storm	Tuesday Thunder storm Hot!	Tuesday night Fog late	Wednesday Fog a.m.	Wednesday night Fog late	Thursday Fog a.m.
<.1 in.	<.1 in.	<.1 in.	<.1 in.	<.1 in.
Low: 80°	High: 97°	Low: 78°	High: 93°	Low: 73°	High: 90°	Low: 69°	High: 91°
	Heat: 114°		Heat: 105°		Heat: 98°		Heat: 96°
WSW 4-23 mph	SW 6-24 mph	WSW 5-17 mph	NW→N 6-23 mph	N→ENE 4-20 mph	ENE 4-24 mph	E 4-21 mph	ESE 4-23 mph
	UV: 9 Very High		UV: 9 Very High		UV: 9 Very High		UV: 8 Very High

Tonight	Partly cloudy. Light to moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Warm. Low 80°. Wind west-southwest around 4 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Monday	Partly to mostly sunny. Patchy light fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. Very hot. High 97°. Heat index up to 114°. UV index up to 9. Wind southwest around 6 mph, gusting to 24 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Monday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Scattered thunderstorms likely, some possibly severe. Low 78°. Wind west-southwest around 5 mph, gusting to 17 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 93°. Heat index up to 105°. UV index up to 9. Wind northwest around 6 mph, gusting to 23 mph, in the morning, becoming north in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Partly cloudy. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 73°. Wind north around 4 mph, gusting to 20 mph, in the evening, becoming east-northeast after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Partly cloudy in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Hot. High 90°. Heat index up to 98°. UV index up to 9. Wind east-northeast around 4 mph, gusting to 24 mph.
Wednesday night	Clear. Patchy light fog after midnight. Low 69°. Wind east around 4 mph, gusting to 21 mph.
Thursday	Partly cloudy. Patchy light fog in the morning. Hot. High 91°. Heat index up to 96°. UV index up to 8. Wind east-southeast around 4 mph, gusting to 23 mph.
Thursday night	Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog after midnight. A chance of rain after midnight. Low 69°. Wind southeast around 4 mph, gusting to 18 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Friday	Cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning, then patchy light fog in the afternoon. A chance of rain in the morning, then rain likely in the afternoon. Scattered thundershowers possible. High 84°. UV index up to 6. Wind southeast around 6 mph, gusting to 24 mph. Chance of precipitation 70 percent. Precipitation mostly around half an inch.
Friday night	Partly to mostly cloudy in the evening, becoming dense overcast after midnight. Moderate fog in the evening, then light to moderate fog after midnight. Rain very likely. Scattered thunderstorms likely. Low 72°. Wind east around 8 mph, gusting to 20 mph. Chance of precipitation 90 percent. Precipitation mostly between 1 and 2 inches.
Saturday	Cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thunderstorms likely. High 83°. UV index up to 9. Wind northeast around 6 mph, gusting to 23 mph, in the morning, becoming 9 mph, gusting to 27 mph, in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Mostly clear in the evening, becoming clear after midnight. Moderate fog after midnight. Low 69°. Wind northeast around 8 mph, gusting to 25 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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