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: Thursday, 10-Sep-2026 05:00 am

Today Rain likely	Tonight Mostly Cloudy	Friday Mostly Cloudy	Friday night Fog	Saturday Fog a.m.	Saturday night Partly Cloudy	Sunday Chance rain	Sunday night Fog
.35 in.		<.1 in.				.1 in.	<.1 in.
High: 77°	Low: 66°	High: 80°	Low: 66°	High: 89°	Low: 66°	High: 85°	Low: 64°
				Heat: 94°
ENE→NNW 2-17 mph	NE 1-15 mph	E 4-21 mph	ESE→SSE 4-16 mph	SSW→W 5-23 mph	SSW→W calm	E→NNW 3-17 mph	NE 3 mph
		UV: 4 Medium		UV: 6 High		UV: 5 Medium

Today	Dense overcast in the morning, becoming cloudy in the afternoon. Rain likely in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. High 77°. Wind east-northeast around 2 mph, gusting to 17 mph, in the morning, becoming north-northwest in the afternoon. Chance of precipitation 70 percent. Precipitation mostly between a quarter and half an inch.
Tonight	Mostly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 66°. Wind northeast around 1 mph, gusting to 15 mph.
Friday	Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. A chance of rain. High 80°. UV index up to 4. Wind east around 4 mph, gusting to 21 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Fair in the evening, becoming fair to partly cloudy after midnight. Patchy light fog. Low 66°. Wind east-southeast around 4 mph, gusting to 16 mph, in the evening, becoming south-southeast after midnight.
Saturday	Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 89°. Heat index up to 94°. UV index up to 6. Wind south-southwest around 5 mph, gusting to 23 mph, in the morning, becoming west in the afternoon.
Saturday night	Mostly clear in the evening, becoming fair to partly cloudy after midnight. Low 66°. Wind south-southwest near calm in the evening, becoming west after midnight.
Sunday	Partly cloudy in the morning, becoming mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Warm. High 85°. UV index up to 5. Wind east around 3 mph, gusting to 17 mph, in the morning, becoming north-northwest in the afternoon. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Sunday night	Fair to partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog. A slight chance of rain in the evening. Low 64°. Wind northeast around 3 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Monday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. Unusually hot. High 90°. Heat index up to 96°. UV index up to 7. Wind east-southeast around 5 mph, gusting to 17 mph, in the morning, becoming south-southeast around 9 mph, gusting to 22 mph, in the afternoon.
Monday night	Clear. Patchy light fog after midnight. Low 68°. Wind south around 8 mph, gusting to 18 mph.
Tuesday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Very hot. High 92°. Heat index up to 99°. UV index up to 6. Wind south-southwest around 7 mph, gusting to 21 mph.
Tuesday night	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A slight chance of rain. Precipitation showery or intermittent. Warm. Low 71°. Wind south-southeast around 5 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the afternoon. Precipitation showery or intermittent. Very hot. High 93°. Heat index up to 101°. UV index up to 5. Wind southwest around 3 mph, gusting to 19 mph, in the morning, becoming 7 mph, gusting to 21 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night	Mostly cloudy in the evening, becoming cloudy after midnight. Light to moderate fog. A chance of rain in the evening, then a slight chance of rain after midnight. Precipitation showery or intermittent. Warm. Low 72°. Wind west-southwest around 4 mph in the evening, becoming north after midnight. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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