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, 14-Aug-2026 05:00 am

Today Chance rain Hot!	Tonight Partly Cloudy	Saturday Partly Cloudy Hot!	Saturday night Fog late	Sunday Partly Cloudy Hot!	Sunday night Chance rain	Monday Fog a.m.	Monday night Fog late
.1 in.	<.1 in.	<.1 in.	<.1 in.		<.25 in.	<.1 in.	<.1 in.
High: 99°	Low: 78°	High: 98°	Low: 77°	High: 96°	Low: 73°	High: 86°	Low: 69°
Heat: 113°		Heat: 112°		Heat: 106°		Heat: 92°
SSW 4-23 mph	SE→S 5-16 mph	SW 6-22 mph	SSW 4 mph	W 6-23 mph	NNW 4-18 mph	NNW 5-22 mph	NE 2-18 mph
UV: 7 High		UV: 8 Very High		UV: 8 Very High		UV: 6 High

Today	Partly cloudy. A chance of rain in the morning, then a slight chance of rain in the afternoon. Precipitation showery or intermittent. Very hot. High 99°. Heat index up to 113°. UV index up to 7. Wind south-southwest around 4 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Tonight	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. A chance of rain. Warm. Low 78°. Wind southeast around 5 mph, gusting to 16 mph, in the evening, becoming south after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Partly cloudy. A chance of rain. Very hot. High 98°. Heat index up to 112°. UV index up to 8. Wind southwest around 6 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. A chance of rain. Warm. Low 77°. Wind south-southwest around 4 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Sunday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 96°. Heat index up to 106°. UV index up to 8. Wind west around 6 mph, gusting to 23 mph.
Sunday night	Partly cloudy. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Low 73°. Wind north-northwest around 4 mph, gusting to 18 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Monday	Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. A slight chance of rain. High 86°. Heat index up to 92°. UV index up to 6. Wind north-northwest around 5 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Low 69°. Wind northeast around 2 mph, gusting to 18 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 90°. Heat index up to 97°. UV index up to 8. Wind southeast around 3 mph, gusting to 21 mph.
Tuesday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Low 72°. Wind southeast around 6 mph, gusting to 15 mph.
Wednesday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 92°. Heat index up to 100°. UV index up to 9. Wind south-southwest around 8 mph, gusting to 26 mph, in the morning, becoming west-northwest in the afternoon.
Wednesday night	Partly to mostly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Low 71°. Wind northeast around 4 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Thursday	Mostly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Light to moderate fog in the morning. Rain likely. Precipitation showery or intermittent. High 81°. UV index up to 6. Wind east-northeast around 4 mph, gusting to 17 mph, in the morning, becoming 8 mph, gusting to 21 mph, in the afternoon. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch.
Thursday night	Cloudy in the evening, becoming mostly cloudy to cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely in the evening, then a chance of rain after midnight. Scattered thundershowers possible. Low 73°. Wind east-southeast around 5 mph, gusting to 17 mph. Chance of precipitation 80 percent. Precipitation mostly between half an inch and one inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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