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: Tuesday, 01-Sep-2026 05:00 am

Today Sunny Hot!	Tonight Clear	Wednesday Sunny Hot!	Wednesday night Partly Cloudy	Thursday Sunny Hot!	Thursday night Clear	Friday Partly Cloudy Hot!	Friday night Fair

High: 101°	Low: 73°	High: 100°	Low: 72°	High: 99°	Low: 72°	High: 98°	Low: 72°
Heat: 106°		Heat: 106°		Heat: 106°		Heat: 106°
SW 5-24 mph	S 2-16→6 mph	SSW 6-24 mph	S 5-17 mph	SW 5-23 mph	S 4 mph	SW 4-21 mph	SE→SSW 3 mph
UV: 8 Very High		UV: 8 Very High		UV: 8 Very High		UV: 6 High

Today	Sunny. Near record heat. High 101°. Heat index up to 106°. UV index up to 8. Wind southwest around 5 mph, gusting to 24 mph.
Tonight	Clear. Warm. Low 73°. Wind south around 2 mph, gusting to 16 mph, in the evening, becoming 6 mph after midnight.
Wednesday	Sunny. Extremely hot. High 100°. Heat index up to 106°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 24 mph.
Wednesday night	Fair to partly cloudy in the evening, becoming clear after midnight. Low 72°. Wind south around 5 mph, gusting to 17 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.
Friday	Sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 98°. Heat index up to 106°. UV index up to 6. Wind southwest around 4 mph, gusting to 21 mph.
Friday night	Fair. Low 72°. Wind southeast around 3 mph in the evening, becoming south-southwest after midnight.
Saturday	Partly to mostly sunny. Very hot. High 97°. Heat index up to 105°. UV index up to 8. Wind north-northwest around 3 mph, gusting to 19 mph, in the morning, becoming west in the afternoon.
Saturday night	Partly cloudy. Warm. Low 72°. Wind north around 2 mph in the evening, becoming east after midnight.
Sunday	Partly cloudy. Very hot. High 93°. Heat index up to 100°. UV index up to 6. Wind north-northeast around 4 mph, gusting to 22 mph.
Sunday night	Fair. Low 70°. Wind east around 3 mph, gusting to 17 mph, in the evening, becoming southwest after midnight.
Monday	Partly cloudy in the morning, becoming mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Very hot. High 94°. Heat index up to 100°. UV index up to 6. Wind south around 6 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a quarter of an inch.
Monday night	Mostly cloudy to cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog in the evening. A chance of rain in the evening, then a slight chance of rain after midnight. Warm. Low 74°. Wind southeast around 6 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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