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: Wednesday, 02-Sep-2026 05:00 am

Today Mostly Sunny Hot!	Tonight Clear	Thursday Sunny Hot!	Thursday night Mostly Clear	Friday Mostly Sunny Hot!	Friday night Partly Cloudy	Saturday Mostly Sunny Hot!	Saturday night Fog late
						<.1 in.
High: 102°	Low: 75°	High: 100°	Low: 74°	High: 99°	Low: 73°	High: 96°	Low: 72°
Heat: 110°		Heat: 108°		Heat: 107°		Heat: 105°
SW 5-24 mph	S 4-19 mph	SW 5-24 mph	S 5-18 mph	WSW 4-21 mph	S 2 mph	SW→N 3-20 mph	E 3 mph
UV: 8 Very High		UV: 8 Very High		UV: 6 High		UV: 8 Very High

Today	Sunny in the morning, becoming mostly sunny in the afternoon. Near record heat. High 102°. Heat index up to 110°. UV index up to 8. Wind southwest around 5 mph, gusting to 24 mph.
Tonight	Clear. Warm. Low 75°. Wind south around 4 mph, gusting to 19 mph.
Thursday	Sunny. Extremely hot. High 100°. Heat index up to 108°. UV index up to 8. Wind southwest around 5 mph, gusting to 24 mph.
Thursday night	Clear in the evening, becoming mostly clear after midnight. Warm. Low 74°. Wind south around 5 mph, gusting to 18 mph.
Friday	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 6. Wind west-southwest around 4 mph, gusting to 21 mph.
Friday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Warm. Low 73°. Wind south around 2 mph.
Saturday	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. A chance of rain. Precipitation showery or intermittent. Very hot. High 96°. Heat index up to 105°. UV index up to 8. Wind southwest around 3 mph, gusting to 20 mph, in the morning, becoming north in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 72°. Wind east around 3 mph.
Sunday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Very hot. High 93°. Heat index up to 100°. UV index up to 7. Wind east around 5 mph, gusting to 22 mph.
Sunday night	Fair to partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 68°. Wind east-northeast around 5 mph, gusting to 17 mph.
Monday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Very hot. High 91°. Heat index up to 97°. UV index up to 7. Wind east around 5 mph, gusting to 23 mph.
Monday night	Partly cloudy in the evening, becoming fair after midnight. Low 68°. Wind southeast around 6 mph, gusting to 17 mph.
Tuesday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Near record heat. High 101°. Heat index up to 108°. UV index up to 7. Wind south-southwest around 9 mph, gusting to 24 mph.
Tuesday night	Clear. Low 72°. Wind south-southwest around 8 mph, gusting to 20 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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