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: Saturday, 29-Aug-2026 05:00 am

Today Partly Cloudy	Tonight Partly Cloudy	Sunday Mostly Sunny	Sunday night Mostly Clear	Monday Mostly Sunny	Monday night Mostly Clear	Tuesday Sunny Hot!	Tuesday night Fog late

High: 89°	Low: 62°	High: 94°	Low: 67°	High: 96°	Low: 70°	High: 97°	Low: 70°
						Heat: 103°
S 5-23 mph	S 6-18 mph	S 7-23 mph	S 6-16 mph	S→SW 6-20 mph	S 5 mph	SSW 6-19 mph	S 5 mph
UV: 7 High		UV: 8 Very High		UV: 8 Very High		UV: 8 Very High

Today	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Hot. High 89°. UV index up to 7. Wind south around 5 mph, gusting to 23 mph.
Tonight	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Low 62°. Wind south around 6 mph, gusting to 18 mph.
Sunday	Partly to mostly sunny. Very hot. High 94°. UV index up to 8. Wind south around 7 mph, gusting to 23 mph.
Sunday night	Mostly clear in the evening, becoming clear after midnight. Low 67°. Wind south around 6 mph, gusting to 16 mph.
Monday	Mostly sunny in the morning, becoming sunny in the afternoon. Very hot. High 96°. UV index up to 8. Wind south around 6 mph, gusting to 20 mph, in the morning, becoming southwest in the afternoon.
Monday night	Fair in the evening, becoming mostly clear after midnight. Low 70°. Wind south around 5 mph.
Tuesday	Sunny. Very hot. High 97°. Heat index up to 103°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 19 mph.
Tuesday night	Clear. Patchy light fog after midnight. Low 70°. Wind south around 5 mph.
Wednesday	Sunny. Patchy light fog in the morning. Very hot. High 98°. Heat index up to 106°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 21 mph.
Wednesday night	Clear. Low 72°. Wind south around 4 mph.
Thursday	Mostly sunny. Extremely hot. High 100°. Heat index up to 109°. UV index up to 8. Wind southwest around 5 mph, gusting to 20 mph.
Thursday night	Partly cloudy in the evening, becoming clear after midnight. Warm. Low 74°. Wind southwest around 4 mph in the evening, becoming 8 mph after midnight.
Friday	Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Extremely hot. High 100°. Heat index up to 111°. UV index up to 7. Wind south-southwest around 8 mph, gusting to 21 mph.
Friday night	Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Warm. Low 77°. Wind north-northeast around 6 mph in the evening, becoming south-southwest around 2 mph after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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