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 05:00 am

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

High: 100°	Low: 72°	High: 101°	Low: 71°	High: 99°	Low: 71°	High: 99°	Low: 72°
		Heat: 105°		Heat: 104°		Heat: 106°
SSW 7-25 mph	SSW 5-17 mph	SSW 5-23 mph	S 2→6 mph	SW 6-24 mph	S 4 mph	SW 5-23 mph	S 4 mph
UV: 9 Very High		UV: 8 Very High		UV: 8 Very High		UV: 8 Very High

Today	Sunny. Extremely hot. High 100°. UV index up to 9. Wind south-southwest around 7 mph, gusting to 25 mph.
Tonight	Clear. Low 72°. Wind south-southwest around 5 mph, gusting to 17 mph.
Tuesday	Sunny. Extremely hot. High 101°. Heat index up to 105°. UV index up to 8. Wind south-southwest around 5 mph, gusting to 23 mph.
Tuesday night	Clear. Low 71°. Wind south around 2 mph in the evening, becoming 6 mph after midnight.
Wednesday	Sunny. Extremely hot. High 99°. Heat index up to 104°. UV index up to 8. Wind southwest around 6 mph, gusting to 24 mph.
Wednesday night	Clear. Low 71°. Wind south around 4 mph.
Thursday	Sunny in the morning, becoming mostly sunny in the afternoon. 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	Clear. Low 72°. Wind south around 4 mph.
Friday	Sunny. Extremely hot. High 99°. Heat index up to 107°. UV index up to 8. Wind south-southwest around 4 mph, gusting to 20 mph.
Friday night	Fair in the evening, becoming fair to partly cloudy after midnight. Low 72°. Wind south-southwest around 3 mph.
Saturday	Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. A slight chance of rain in the afternoon. Extremely hot. High 100°. Heat index up to 107°. UV index up to 7. Wind west around 4 mph, gusting to 18 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. A slight chance of rain after midnight. Warm. Low 73°. Wind north around 4 mph in the evening, becoming east after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Sunday	Cloudy in the morning, becoming partly cloudy in the afternoon. A chance of rain in the morning, then a slight chance of rain in the afternoon. Hot. High 86°. UV index up to 6. Wind east-southeast around 7 mph, gusting to 26 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Low 72°. Wind east-southeast around 6 mph, gusting to 22 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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