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, 04-Aug-2026 04:00 pm

Tonight Fog late	Wednesday Chance rain	Wednesday night Rain likely	Thursday Chance rain	Thursday night Chance rain	Friday Chance rain	Friday night Chance rain	Saturday Fog a.m. Hot!
<.1 in.	.1 in.	.25 in.	<.25 in.	<.25 in.	<.1 in.	.1 in.	<.1 in.
Low: 71°	High: 89°	Low: 73°	High: 88°	Low: 73°	High: 90°	Low: 73°	High: 91°
	Heat: 95°		Heat: 94°		Heat: 98°		Heat: 100°
SE 5-22 mph	S→W 5-22 mph	NNE 2 mph	S 4-23 mph	SSE 4-20 mph	WSW 6-22 mph	SW 4-17 mph	WSW 4-22 mph
	UV: 8 Very High		UV: 8 Very High		UV: 6 High		UV: 8 Very High

Tonight	Fair in the evening, becoming fair to partly cloudy after midnight. Moderate fog after midnight. A chance of rain. Low 71°. Wind southeast around 5 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. High 89°. Heat index up to 95°. UV index up to 8. Wind south around 5 mph, gusting to 22 mph, in the morning, becoming west in the afternoon. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Wednesday night	Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. Rain likely. Precipitation showery or intermittent. Low 73°. Wind north-northeast around 2 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.
Thursday	Cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Precipitation showery or intermittent. High 88°. Heat index up to 94°. UV index up to 8. Wind south around 4 mph, gusting to 23 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch.
Thursday night	Partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Precipitation showery or intermittent. Low 73°. Wind south-southeast around 4 mph, gusting to 20 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Friday	Mostly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Hot. High 90°. Heat index up to 98°. UV index up to 6. Wind west-southwest around 6 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Low 73°. Wind southwest around 4 mph, gusting to 17 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Saturday	Mostly cloudy in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. A chance of rain. Hot. High 91°. Heat index up to 100°. UV index up to 8. Wind west-southwest around 4 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Clear in the evening, becoming fair after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 73°. Wind south-southeast around 4 mph, gusting to 18 mph.
Sunday	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. Hot. High 94°. Heat index up to 103°. UV index up to 8. Wind south-southeast around 8 mph, gusting to 24 mph.
Sunday night	Clear. Patchy light fog after midnight. Low 73°. Wind south-southwest around 6 mph, gusting to 18 mph.
Monday	Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 105°. UV index up to 8. Wind south-southwest around 9 mph, gusting to 24 mph.
Monday night	Partly to mostly cloudy. A chance of rain. Precipitation showery or intermittent. Low 75°. Wind south-southwest around 9 mph, gusting to 16 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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