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: Thursday, 03-Sep-2026 05:00 am

Today Sunny Hot!	Tonight Mostly Clear	Friday Sunny Hot!	Friday night Partly Cloudy	Saturday Mostly Sunny Hot!	Saturday night Partly Cloudy	Sunday Sunny	Sunday night Partly Cloudy

High: 101°	Low: 75°	High: 100°	Low: 75°	High: 99°	Low: 70°	High: 91°	Low: 65°
Heat: 109°		Heat: 108°		Heat: 107°		Heat: 96°
SW 6-25 mph	S 4-19 mph	SW 5-24 mph	SSW 3 mph	WSW→NW 4-22 mph	NNE 4 mph	NNE 7-25 mph	NE→E 6-20 mph
UV: 8 Very High		UV: 7 High		UV: 7 High		UV: 7 High

Today	Sunny. Near record heat. High 101°. Heat index up to 109°. UV index up to 8. Wind southwest around 6 mph, gusting to 25 mph.
Tonight	Mostly clear in the evening, becoming clear after midnight. Warm. Low 75°. Wind south around 4 mph, gusting to 19 mph.
Friday	Sunny. Extremely hot. High 100°. Heat index up to 108°. UV index up to 7. Wind southwest around 5 mph, gusting to 24 mph.
Friday night	Fair to partly cloudy. Warm. Low 75°. Wind south-southwest around 3 mph.
Saturday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Extremely hot. High 99°. Heat index up to 107°. UV index up to 7. Wind west-southwest around 4 mph, gusting to 22 mph, in the morning, becoming northwest in the afternoon.
Saturday night	Partly cloudy in the evening, becoming clear after midnight. Low 70°. Wind north-northeast around 4 mph.
Sunday	Sunny. Hot. High 91°. Heat index up to 96°. UV index up to 7. Wind north-northeast around 7 mph, gusting to 25 mph.
Sunday night	Fair to partly cloudy in the evening, becoming fair after midnight. Low 65°. Wind northeast around 6 mph, gusting to 20 mph, in the evening, becoming east after midnight.
Monday	Sunny. Hot. High 90°. UV index up to 8. Wind east around 5 mph, gusting to 24 mph.
Monday night	Fair to partly cloudy in the evening, becoming clear after midnight. Low 64°. Wind east around 5 mph, gusting to 18 mph.
Tuesday	Sunny. Very hot. High 94°. UV index up to 8. Wind southeast around 4 mph, gusting to 21 mph.
Tuesday night	Mostly clear in the evening, becoming clear after midnight. Low 67°. Wind south-southeast around 7 mph.
Wednesday	Sunny. Near record heat. High 102°. Heat index up to 107°. UV index up to 7. Wind west-southwest around 9 mph, gusting to 24 mph.
Wednesday night	Partly cloudy in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 69°. Wind south-southwest around 8 mph, gusting to 19 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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