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, 15-Sep-2026 04:00 pm

Tonight Partly Cloudy	Wednesday Mostly Sunny Hot!	Wednesday night Fog late	Thursday Sunny Hot!	Thursday night Partly Cloudy	Friday Fog a.m.	Friday night Partly Cloudy	Saturday Mostly Cloudy
<.1 in.				<.1 in.
Low: 74°	High: 99°	Low: 69°	High: 100°	Low: 68°	High: 95°	Low: 68°	High: 96°
	Heat: 106°		Heat: 106°		Heat: 99°
NE→S 4-22 mph	SSW→WSW 4-24 mph	S 4-17 mph	SW→WNW 5-24 mph	NNE 2 mph	ENE 3-20 mph	SSE 4 mph	SW 7-20 mph
	UV: 7 High		UV: 7 High		UV: 7 High		UV: 6 High

Tonight	Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. A slight chance of rain. Warm. Low 74°. Wind northeast around 4 mph, gusting to 22 mph, in the evening, becoming south after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Near record heat. High 99°. Heat index up to 106°. UV index up to 7. Wind south-southwest around 4 mph, gusting to 24 mph, in the morning, becoming west-southwest in the afternoon.
Wednesday night	Partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Warm. Low 69°. Wind south around 4 mph, gusting to 17 mph.
Thursday	Sunny. Near record heat. High 100°. Heat index up to 106°. UV index up to 7. Wind southwest around 5 mph, gusting to 24 mph, in the morning, becoming west-northwest in the afternoon.
Thursday night	Fair to partly cloudy in the evening, becoming fair after midnight. A slight chance of rain. Low 68°. Wind north-northeast around 2 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Friday	Sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 95°. Heat index up to 99°. UV index up to 7. Wind east-northeast around 3 mph, gusting to 20 mph.
Friday night	Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 68°. Wind south-southeast around 4 mph.
Saturday	Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Very hot. High 96°. UV index up to 6. Wind southwest around 7 mph, gusting to 20 mph.
Saturday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Low 66°. Wind south around 2 mph in the evening, becoming west-southwest after midnight.
Sunday	Sunny. Very hot. High 92°. UV index up to 7. Wind west around 3 mph, gusting to 18 mph, in the morning, becoming 8 mph, gusting to 22 mph, in the afternoon.
Sunday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Low 66°. Wind northwest around 3 mph.
Monday	Partly to mostly cloudy in the morning, becoming sunny in the afternoon. Unusually hot. High 88°. UV index up to 6. Wind west-northwest around 4 mph, gusting to 24 mph, in the morning, becoming 9 mph, gusting to 25 mph, in the afternoon.
Monday night	Clear in the evening, becoming fair to partly cloudy after midnight. Low 60°. Wind northwest around 4 mph, gusting to 19 mph, in the evening, becoming northeast after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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