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, 05-Aug-2026 05:00 am

Today Chance rain	Tonight Chance rain	Thursday Chance rain	Thursday night Chance rain	Friday Fog a.m.	Friday night Fog late	Saturday Fog a.m.	Saturday night Fog late
.1 in.	.25 in.	<.25 in.	<.25 in.			<.1 in.
High: 90°	Low: 71°	High: 85°	Low: 73°	High: 91°	Low: 73°	High: 91°	Low: 73°
Heat: 94°				Heat: 98°		Heat: 99°
SSW 5-23 mph	S→NNW 2 mph	S 5-22 mph	SSE 5-17 mph	SW 6-23 mph	SW 4-20 mph	WSW 4-22 mph	SE 4-17 mph
UV: 8 Very High		UV: 6 High		UV: 7 High		UV: 7 High

Today	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. A chance of rain. Hot. High 90°. Heat index up to 94°. UV index up to 8. Wind south-southwest around 5 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Tonight	Partly to mostly cloudy in the evening, becoming mostly 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 71°. Wind south around 2 mph in the evening, becoming north-northwest after midnight. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch.
Thursday	Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. High 85°. UV index up to 6. Wind south around 5 mph, gusting to 22 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Thursday night	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain. Low 73°. Wind south-southeast around 5 mph, gusting to 17 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Friday	Partly to mostly cloudy. Light to moderate fog in the morning. Hot. High 91°. Heat index up to 98°. UV index up to 7. Wind southwest around 6 mph, gusting to 23 mph.
Friday night	Fair in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. Low 73°. Wind southwest around 4 mph, gusting to 20 mph.
Saturday	Mostly cloudy in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A slight chance of rain. Hot. High 91°. Heat index up to 99°. UV index up to 7. Wind west-southwest around 4 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Fair in the evening, becoming fair to partly cloudy after midnight. Light to moderate fog after midnight. Low 73°. Wind southeast around 4 mph, gusting to 17 mph.
Sunday	Partly cloudy in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 93°. Heat index up to 102°. UV index up to 8. Wind south around 5 mph, gusting to 19 mph, in the morning, becoming 9 mph, gusting to 22 mph, in the afternoon.
Sunday night	Mostly clear in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 74°. Wind south around 8 mph, gusting to 18 mph.
Monday	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 106°. UV index up to 7. Wind south-southwest around 9 mph, gusting to 25 mph.
Monday night	Mostly clear in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 74°. Wind southwest around 7 mph, gusting to 17 mph.
Tuesday	Mostly cloudy to cloudy in the morning, becoming partly to mostly cloudy in the afternoon. A slight chance of rain in the morning, then a chance of rain in the afternoon. Hot. High 91°. Heat index up to 98°. UV index up to 7. Wind east-northeast around 6 mph, gusting to 24 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Tuesday night	Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Light to moderate fog. Rain likely. Low 74°. Wind east-southeast around 6 mph, gusting to 19 mph, in the evening, becoming south-southeast after midnight. Chance of precipitation 70 percent. Precipitation mostly between 1 and 2 inches.

WXSIM forecast formatting script by Saratoga-Weather.org.

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