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 04:00 pm

Tonight Clear	Thursday Mostly Sunny Hot!	Thursday night Partly Cloudy	Friday Sunny Hot!	Friday night Mostly Clear	Saturday Partly Cloudy Hot!	Saturday night Fog late	Sunday Fog a.m.
						<.1 in.
Low: 74°	High: 99°	Low: 73°	High: 98°	Low: 72°	High: 97°	Low: 70°	High: 90°
	Heat: 105°		Heat: 106°		Heat: 104°		Heat: 96°
SSW 4-22 mph	SSW 6-24 mph	S 5-18 mph	SW 4-23 mph	SSW 2 mph	SE→NNW 4-21 mph	NE 3-15 mph	NE 3-18→6-22 mph
	UV: 8 Very High		UV: 8 Very High		UV: 7 High		UV: 8 Very High

Tonight	Fair in the evening, becoming clear after midnight. Warm. Low 74°. Wind south-southwest around 4 mph, gusting to 22 mph.
Thursday	Sunny in the morning, becoming mostly sunny in the afternoon. Extremely hot. High 99°. Heat index up to 105°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 24 mph.
Thursday night	Fair to partly cloudy in the evening, becoming fair after midnight. Warm. Low 73°. Wind south around 5 mph, gusting to 18 mph.
Friday	Sunny. Extremely hot. High 98°. Heat index up to 106°. UV index up to 8. Wind southwest around 4 mph, gusting to 23 mph.
Friday night	Mostly clear in the evening, becoming fair after midnight. Warm. Low 72°. Wind south-southwest around 2 mph.
Saturday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Very hot. High 97°. Heat index up to 104°. UV index up to 7. Wind southeast around 4 mph, gusting to 21 mph, in the morning, becoming north-northwest in the afternoon.
Saturday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. A chance of rain. Low 70°. Wind northeast around 3 mph, gusting to 15 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Sunday	Mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Hot. High 90°. Heat index up to 96°. UV index up to 8. Wind northeast around 3 mph, gusting to 18 mph, in the morning, becoming 6 mph, gusting to 22 mph, in the afternoon.
Sunday night	Partly cloudy in the evening, becoming fair after midnight. Moderate fog after midnight. A slight chance of rain. Low 67°. Wind east-northeast around 6 mph, gusting to 18 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Monday	Sunny. Light to moderate fog in the morning. Hot. High 89°. Heat index up to 94°. UV index up to 7. Wind east around 5 mph, gusting to 22 mph.
Monday night	Mostly clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 65°. Wind east-southeast around 5 mph, gusting to 16 mph.
Tuesday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Extremely hot. High 99°. Heat index up to 104°. UV index up to 7. Wind southwest around 7 mph, gusting to 20 mph, in the morning, becoming 10 mph, gusting to 24 mph, in the afternoon.
Tuesday night	Partly cloudy in the evening, becoming clear after midnight. Low 71°. Wind southwest around 7 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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