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, 16-Aug-2026 04:00 pm

Tonight Thunder storm	Monday Rain likely	Monday night Rain likely	Tuesday Chance rain	Tuesday night Rain likely	Wednesday Rain likely	Wednesday night Rain likely	Thursday Rain likely
.5 in.	<.1 in.	<.1 in.	<.1 in.	.25 in.	.5 in.	.25 in.	.5 in.
Low: 74°	High: 84°	Low: 69°	High: 88°	Low: 70°	High: 85°	Low: 70°	High: 79°
			Heat: 94°
NNW 3-16 mph	NNW 6-25 mph	NNW→WNW 2-19 mph	SSW 3-21 mph	E 3 mph	S→ENE 2-17 mph	NE 3-15 mph	NE 3-19 mph
	UV: 7 High		UV: 8 Very High		UV: 8 Very High		UV: 6 High

Tonight	Mostly cloudy in the evening, becoming partly cloudy after midnight. Moderate fog. Rain very likely. Scattered thunderstorms likely. Low 74°. Wind north-northwest around 3 mph, gusting to 16 mph. Chance of precipitation 90 percent. Precipitation mostly around half an inch.
Monday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. Rain likely. High 84°. UV index up to 7. Wind north-northwest around 6 mph, gusting to 25 mph. Chance of precipitation 60 percent. Precipitation mostly less than a tenth of an inch.
Monday night	Partly cloudy. Patchy light fog in the evening, then moderate fog after midnight. Rain likely. Low 69°. Wind north-northwest around 2 mph, gusting to 19 mph, in the evening, becoming west-northwest after midnight. Chance of precipitation 60 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. A chance of rain. Hot. High 88°. Heat index up to 94°. UV index up to 8. Wind south-southwest around 3 mph, gusting to 21 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Mostly clear in the evening, becoming mostly cloudy after midnight. Patchy light fog after midnight. Rain likely after midnight. Precipitation showery or intermittent. Low 70°. Wind east around 3 mph. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch.
Wednesday	Mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Rain likely in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. High 85°. UV index up to 8. Wind south around 2 mph, gusting to 17 mph, in the morning, becoming east-northeast in the afternoon. Chance of precipitation 90 percent. Precipitation mostly around half an inch.
Wednesday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Moderate fog in the evening, then light to moderate fog after midnight. Rain likely in the evening, then a chance of rain after midnight. Precipitation showery or intermittent. Low 70°. Wind northeast around 3 mph, gusting to 15 mph. Chance of precipitation 80 percent. Precipitation mostly around a quarter of an inch.
Thursday	Dense overcast in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning, then patchy light fog in the afternoon. Rain likely in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. High 79°. UV index up to 6. Wind northeast around 3 mph, gusting to 19 mph. Chance of precipitation 90 percent. Precipitation mostly around half an inch.
Thursday night	Fair to partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Low 67°. Wind northeast around 2 mph, gusting to 16 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Friday	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. High 84°. UV index up to 7. Wind northeast around 4 mph, gusting to 22 mph.
Friday night	Clear in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Low 66°. Wind east-northeast around 2 mph, gusting to 16 mph, in the evening, becoming south-southwest after midnight.
Saturday	Sunny. Light to moderate fog in the morning. High 86°. UV index up to 8. Wind southwest around 2 mph, gusting to 19 mph.
Saturday night	Mostly clear in the evening, becoming clear after midnight. Light to moderate fog after midnight. Low 67°. Wind south around 2 mph in the evening, becoming west-northwest after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

Powered by Davis Vantage Pro2 and CumulusMX v 4.6.4 (b4128) MXUI Template v 2.2.6 by Silver Acorn Valid HTML5