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, 31-Aug-2026 04:00 pm

Tonight Clear	Tuesday Sunny Hot!	Tuesday night Clear	Wednesday Sunny Hot!	Wednesday night Mostly Clear	Thursday Sunny Hot!	Thursday night Clear	Friday Sunny Hot!

Low: 72°	High: 99°	Low: 72°	High: 98°	Low: 72°	High: 99°	Low: 72°	High: 98°
	Heat: 104°		Heat: 105°		Heat: 106°		Heat: 107°
SSW 5-22 mph	SSW 5-22 mph	S 2→6 mph	SW 6-23 mph	S 4 mph	SW 5-23 mph	S 4-15 mph	SSW 4-22 mph
	UV: 8 Very High		UV: 8 Very High		UV: 8 Very High		UV: 8 Very High

Tonight	Clear. Low 72°. Wind south-southwest around 5 mph, gusting to 22 mph.
Tuesday	Sunny. Extremely hot. High 99°. Heat index up to 104°. UV index up to 8. Wind south-southwest around 5 mph, gusting to 22 mph.
Tuesday night	Clear. Low 72°. Wind south around 2 mph in the evening, becoming 6 mph after midnight.
Wednesday	Sunny. Very hot. High 98°. Heat index up to 105°. UV index up to 8. Wind southwest around 6 mph, gusting to 23 mph.
Wednesday night	Mostly clear in the evening, becoming clear after midnight. Low 72°. Wind south around 4 mph.
Thursday	Sunny. Extremely hot. High 99°. Heat index up to 106°. UV index up to 8. Wind southwest around 5 mph, gusting to 23 mph.
Thursday night	Fair in the evening, becoming clear after midnight. Low 72°. Wind south around 4 mph, gusting to 15 mph.
Friday	Sunny. Very hot. High 98°. Heat index up to 107°. UV index up to 8. Wind south-southwest around 4 mph, gusting to 22 mph.
Friday night	Fair to partly cloudy in the evening, becoming mostly clear after midnight. Low 73°. Wind south around 2 mph.
Saturday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 99°. Heat index up to 108°. UV index up to 7. Wind west-southwest around 3 mph, gusting to 19 mph.
Saturday night	Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Moderate fog after midnight. Rain likely. Warm. Low 74°. Wind east-southeast around 2 mph in the evening, becoming 6 mph after midnight. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch.
Sunday	Partly cloudy. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 108°. UV index up to 7. Wind south around 3 mph, gusting to 17 mph.
Sunday night	Partly cloudy in the evening, becoming mostly cloudy to cloudy after midnight. A slight chance of rain. Warm. Low 73°. Wind east-southeast around 8 mph, gusting to 16 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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