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, 14-Sep-2026 04:00 pm

Tonight Fog late	Tuesday Fog a.m.	Tuesday night Partly Cloudy	Wednesday Partly Cloudy Hot!	Wednesday night Fog late	Thursday Fog a.m. Hot!	Thursday night Fog late	Friday Fog a.m. Hot!
		<.1 in.	<.1 in.	<.1 in.
Low: 66°	High: 95°	Low: 69°	High: 94°	Low: 69°	High: 96°	Low: 69°	High: 94°
			Heat: 100°		Heat: 102°		Heat: 100°
SE 8-25 mph	S→SW 7-23 mph	NNE→SSW 3 mph	S 2-22 mph	S 4 mph	SW→WNW 4-21 mph	E calm	E→SE 3-19 mph
	UV: 7 High		UV: 6 High		UV: 7 High		UV: 7 High

Tonight	Clear. Patchy light fog after midnight. Low 66°. Wind southeast around 8 mph, gusting to 25 mph.
Tuesday	Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Very hot. High 95°. UV index up to 7. Wind south around 7 mph, gusting to 23 mph, in the morning, becoming southwest in the afternoon.
Tuesday night	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. A chance of rain. Precipitation showery or intermittent. Warm. Low 69°. Wind north-northeast around 3 mph in the evening, becoming south-southwest after midnight. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Partly cloudy in the morning, becoming mostly sunny in the afternoon. A slight chance of rain. Very hot. High 94°. Heat index up to 100°. UV index up to 6. Wind south around 2 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night	Fair to partly cloudy in the evening, becoming clear after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A slight chance of rain. Warm. Low 69°. Wind south around 4 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Thursday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 102°. UV index up to 7. Wind southwest around 4 mph, gusting to 21 mph, in the morning, becoming west-northwest in the afternoon.
Thursday night	Fair in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Warm. Low 69°. Wind east near calm.
Friday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 94°. Heat index up to 100°. UV index up to 7. Wind east around 3 mph, gusting to 19 mph, in the morning, becoming southeast in the afternoon.
Friday night	Fair to partly cloudy in the evening, becoming clear after midnight. Light to moderate fog after midnight. Low 69°. Wind southeast around 5 mph.
Saturday	Sunny. Moderate fog in the morning. Very hot. High 93°. Heat index up to 100°. UV index up to 7. Wind south around 5 mph, gusting to 21 mph, in the morning, becoming west-southwest in the afternoon.
Saturday night	Clear. Cool. Low 50°. Wind northwest around 3 mph.
Sunday	Sunny. Warm. High 84°. UV index up to 6. Wind northwest around 6 mph, gusting to 15 mph.
Sunday night	Clear. Cool. Low 52°. Wind northwest around 4 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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