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, 17-Aug-2026 05:00 am

Today Thunder storm	Tonight Fog late	Tuesday Fog a.m.	Tuesday night Rain likely	Wednesday Thunder storm	Wednesday night Thunder storm	Thursday Fog a.m.	Thursday night Fog late
<.1 in.	<.1 in.	<.1 in.	.5 in.	<.25 in.	<.1 in.	<.1 in.
High: 85°	Low: 66°	High: 87°	Low: 70°	High: 87°	Low: 70°	High: 81°	Low: 66°
		Heat: 91°		Heat: 92°
NW 7-26 mph	N→E 2-19 mph	S 4-22 mph	SE 4 mph	SSE→NE 4-21 mph	NE 3-19 mph	ENE 5-23 mph	ENE 3-21 mph
UV: 8 Very High		UV: 8 Very High		UV: 7 High		UV: 5 Medium

Today	Partly to mostly sunny. A chance of rain. Scattered thundershowers possible. High 85°. UV index up to 8. Wind northwest around 7 mph, gusting to 26 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tonight	Fair to partly cloudy. Patchy light fog after midnight. A chance of rain. Low 66°. Wind north around 2 mph, gusting to 19 mph, in the evening, becoming east after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. A slight chance of rain. High 87°. Heat index up to 91°. UV index up to 8. Wind south around 4 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Moderate fog after midnight. A slight chance of rain in the evening, then rain likely after midnight. Precipitation showery or intermittent. Low 70°. Wind southeast around 4 mph. Chance of precipitation 60 percent. Precipitation mostly around half an inch.
Wednesday	Partly to mostly cloudy. Light to moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. High 87°. Heat index up to 92°. UV index up to 7. Wind south-southeast around 4 mph, gusting to 21 mph, in the morning, becoming northeast in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Wednesday night	Partly cloudy. Patchy light fog after midnight. A chance of rain. Scattered thundershowers possible. Low 70°. Wind northeast around 3 mph, gusting to 19 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Thursday	Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Precipitation showery or intermittent. High 81°. UV index up to 5. Wind east-northeast around 5 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Thursday night	Fair in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 66°. Wind east-northeast around 3 mph, gusting to 21 mph.
Friday	Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the afternoon. High 86°. UV index up to 7. Wind east-southeast around 1 mph, gusting to 20 mph, in the morning, becoming west-northwest around 5 mph, gusting to 22 mph, in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Mostly clear in the evening, becoming clear after midnight. Patchy light fog. Low 67°. Wind west around 3 mph, gusting to 15 mph.
Saturday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. High 87°. UV index up to 7. Wind west around 4 mph, gusting to 23 mph.
Saturday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Low 69°. Wind south around 4 mph, gusting to 19 mph, in the evening, becoming east-southeast after midnight.
Sunday	Partly cloudy in the morning, becoming mostly cloudy to cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain. Scattered thundershowers possible. High 87°. UV index up to 6. Wind east-northeast around 8 mph, gusting to 23 mph, in the morning, becoming east-southeast in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Precipitation showery or intermittent. Breezy. Low 72°. Wind east-southeast around 12 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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