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 05:00 am

Today Thunder storm Hot!	Tonight Thunder storm	Monday Chance rain	Monday night Fog late	Tuesday Fog a.m.	Tuesday night Fog late	Wednesday Thunder storm	Wednesday night Thunder storm
.1 in.	<.25 in.	.1 in.	<.1 in.			<.1 in.	1.0 in.
High: 94°	Low: 74°	High: 85°	Low: 70°	High: 90°	Low: 71°	High: 90°	Low: 72°
Heat: 105°				Heat: 97°		Heat: 98°
WNW 4-22 mph	NNW 4-16 mph	NNW 4-21 mph	N→E 2-16 mph	S 2-21 mph	SE 3 mph	ESE calm→4-21 mph	ENE 3-17 mph
UV: 8 Very High		UV: 6 High		UV: 8 Very High		UV: 8 Very High

Today	Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 94°. Heat index up to 105°. UV index up to 8. Wind west-northwest around 4 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Tonight	Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Low 74°. Wind north-northwest around 4 mph, gusting to 16 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Monday	Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. High 85°. UV index up to 6. Wind north-northwest around 4 mph, gusting to 21 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Monday night	Fair to partly cloudy. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Low 70°. Wind north around 2 mph, gusting to 16 mph, in the evening, becoming east after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Sunny. Light to moderate fog in the morning. Hot. High 90°. Heat index up to 97°. UV index up to 8. Wind south around 2 mph, gusting to 21 mph.
Tuesday night	Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 71°. Wind southeast around 3 mph.
Wednesday	Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 90°. Heat index up to 98°. UV index up to 8. Wind east-southeast near calm in the morning, becoming 4 mph, gusting to 21 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Moderate fog. Rain likely. Scattered thundershowers possible. Low 72°. Wind east-northeast around 3 mph, gusting to 17 mph. Chance of precipitation 70 percent. Precipitation mostly around an inch.
Thursday	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 a slight chance of rain in the afternoon. Scattered thundershowers possible. High 80°. UV index up to 5. Wind east-northeast around 4 mph, gusting to 18 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.
Thursday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain. Low 68°. Wind north-northeast around 5 mph, gusting to 17 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Friday	Partly to mostly cloudy. Patchy light fog in the morning. High 83°. UV index up to 5. Wind north-northeast around 4 mph, gusting to 21 mph.
Friday night	Fair to partly cloudy in the evening, becoming clear after midnight. Light to moderate fog after midnight. Low 64°. Wind north-northeast around 5 mph, gusting to 17 mph.
Saturday	Mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. High 83°. UV index up to 8. Wind north-northeast around 5 mph, gusting to 23 mph.
Saturday night	Clear in the evening, becoming fair after midnight. Patchy light fog after midnight. Relatively cool. Low 64°. Wind east-southeast around 3 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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