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, 19-Jul-2026 05:00 am

Today Chance rain	Tonight Chance rain	Monday Chance rain Hot!	Monday night Fog late	Tuesday Fog a.m. Hot!	Tuesday night Fog late	Wednesday Fog a.m.	Wednesday night Partly Cloudy
<.25 in.	.1 in.	.1 in.	<.1 in.
High: 91°	Low: 73°	High: 91°	Low: 75°	High: 94°	Low: 70°	High: 87°	Low: 65°
Heat: 99°		Heat: 100°		Heat: 103°
NE 3-22 mph	NE 4-18 mph	ESE→W 3-20 mph	SSW 4 mph	NNW 6-23 mph	NNW 7-19 mph	NNE 7-25 mph	NE 5-24 mph
UV: 8 Very High		UV: 9 Very High		UV: 10 Very High		UV: 7 High

Today	Partly cloudy. A chance of rain. Hot. High 91°. Heat index up to 99°. UV index up to 8. Wind northeast around 3 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Tonight	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 73°. Wind northeast around 4 mph, gusting to 18 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Monday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. A chance of rain. High 91°. Heat index up to 100°. UV index up to 9. Wind east-southeast around 3 mph, gusting to 20 mph, in the morning, becoming west in the afternoon. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Monday night	Partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain. Low 75°. Wind south-southwest around 4 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Mostly sunny. Moderate fog in the morning. Hot. High 94°. Heat index up to 103°. UV index up to 10. Wind north-northwest around 6 mph, gusting to 23 mph.
Tuesday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 70°. Wind north-northwest around 7 mph, gusting to 19 mph.
Wednesday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. High 87°. UV index up to 7. Wind north-northeast around 7 mph, gusting to 25 mph.
Wednesday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Relatively cool. Low 65°. Wind northeast around 5 mph, gusting to 24 mph.
Thursday	Partly cloudy. High 89°. UV index up to 9. Wind east around 4 mph, gusting to 25 mph.
Thursday night	Mostly cloudy in the evening, becoming partly cloudy after midnight. Relatively cool. Low 66°. Wind east around 4 mph, gusting to 23 mph.
Friday	Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. A chance of rain. High 87°. UV index up to 7. Wind east around 5 mph, gusting to 24 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Mostly cloudy in the evening, becoming cloudy after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 69°. Wind east around 8 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Saturday	Mostly cloudy to cloudy in the morning, becoming cloudy in the afternoon. High 82°. UV index up to 5. Wind east around 9 mph, gusting to 27 mph.
Saturday night	Mostly cloudy to cloudy in the evening, becoming fair after midnight. Relatively cool. Low 66°. Wind east around 5 mph, gusting to 24 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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