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, 12-Jul-2026 05:00 am

Today Mostly Sunny	Tonight Fair	Monday Mostly Sunny	Monday night Clear	Tuesday Sunny	Tuesday night Clear	Wednesday Mostly Sunny	Wednesday night Fog late
<.1 in.
High: 87°	Low: 67°	High: 89°	Low: 67°	High: 91°	Low: 69°	High: 93°	Low: 69°
				Heat: 96°		Heat: 97°
N 6-25 mph	NE 4-22 mph	NNE 6-25 mph	NE 3-22 mph	NNE→ENE 5-24 mph	ENE 3-21 mph	NNE→ENE 3-22 mph	ENE→S 2-17 mph
UV: 9 Very High		UV: 9 Very High		UV: 10 Very High		UV: 9 Very High

Today	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. A slight chance of rain. High 87°. UV index up to 9. Wind north around 6 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Tonight	Fair. Relatively cool. Low 67°. Wind northeast around 4 mph, gusting to 22 mph.
Monday	Mostly sunny. High 89°. UV index up to 9. Wind north-northeast around 6 mph, gusting to 25 mph.
Monday night	Fair in the evening, becoming clear after midnight. Relatively cool. Low 67°. Wind northeast around 3 mph, gusting to 22 mph.
Tuesday	Sunny. Hot. High 91°. Heat index up to 96°. UV index up to 10. Wind north-northeast around 5 mph, gusting to 24 mph, in the morning, becoming east-northeast in the afternoon.
Tuesday night	Clear. Low 69°. Wind east-northeast around 3 mph, gusting to 21 mph.
Wednesday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Hot. High 93°. Heat index up to 97°. UV index up to 9. Wind north-northeast around 3 mph, gusting to 22 mph, in the morning, becoming east-northeast in the afternoon.
Wednesday night	Clear. Patchy light fog after midnight. Low 69°. Wind east-northeast around 2 mph, gusting to 17 mph, in the evening, becoming south after midnight.
Thursday	Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 93°. Heat index up to 100°. UV index up to 9. Wind south-southeast around 2 mph, gusting to 21 mph.
Thursday night	Partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Low 71°. Wind south-southeast around 3 mph, gusting to 16 mph, in the evening, becoming southwest after midnight.
Friday	Sunny in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 96°. Heat index up to 103°. UV index up to 9. Wind southwest around 7 mph, gusting to 25 mph.
Friday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 72°. Wind southwest around 8 mph, gusting to 22 mph.
Saturday	Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. Breezy and hot. High 95°. Heat index up to 101°. UV index up to 8. Wind west-southwest around 13 mph, gusting to 30 mph.
Saturday night	Partly to mostly cloudy in the evening, becoming clear after midnight. Light to moderate fog after midnight. A slight chance of rain. Scattered thundershowers possible. Low 69°. Wind north-northwest around 5 mph, gusting to 25 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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