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: Friday, 07-Aug-2026 04:00 pm

Tonight Fog late	Saturday Fog a.m.	Saturday night Fog late	Sunday Fog a.m. Hot!	Sunday night Fog late	Monday Fog a.m. Hot!	Monday night Partly Cloudy	Tuesday Mostly Sunny Hot!
<.1 in.	<.1 in.	<.1 in.	<.1 in.
Low: 73°	High: 89°	Low: 73°	High: 92°	Low: 74°	High: 95°	Low: 75°	High: 97°
	Heat: 96°		Heat: 101°		Heat: 106°		Heat: 107°
SW 5-21 mph	W→ENE 3-21 mph	E→S 3-16 mph	SSW 6-23 mph	SSW 6-18 mph	SSW 8-26 mph	SSW→SE 7-19 mph	SSW 6-24 mph
	UV: 8 Very High		UV: 8 Very High		UV: 8 Very High		UV: 8 Very High

Tonight	Fair to partly cloudy in the evening, becoming fair after midnight. Light to moderate fog in the evening, then moderate to dense fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 73°. Wind southwest around 5 mph, gusting to 21 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Moderate to dense fog in the morning. A chance of rain. Hot. High 89°. Heat index up to 96°. UV index up to 8. Wind west around 3 mph, gusting to 21 mph, in the morning, becoming east-northeast in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday night	Fair in the evening, becoming fair to partly cloudy after midnight. Moderate fog after midnight. A slight chance of rain after midnight. Low 73°. Wind east around 3 mph, gusting to 16 mph, in the evening, becoming south after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Sunday	Mostly sunny in the morning, becoming sunny in the afternoon. Moderate fog in the morning. A chance of rain. Hot. High 92°. Heat index up to 101°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Clear. Light to moderate fog after midnight. Low 74°. Wind south-southwest around 6 mph, gusting to 18 mph.
Monday	Mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. Very hot. High 95°. Heat index up to 106°. UV index up to 8. Wind south-southwest around 8 mph, gusting to 26 mph.
Monday night	Fair to partly cloudy in the evening, becoming fair after midnight. Low 75°. Wind south-southwest around 7 mph, gusting to 19 mph, in the evening, becoming southeast after midnight.
Tuesday	Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Very hot. High 97°. Heat index up to 107°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 24 mph.
Tuesday night	Partly cloudy. Patchy light fog after midnight. A chance of rain after midnight. Precipitation showery or intermittent. Low 74°. Wind south-southwest around 4 mph, gusting to 17 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Wednesday	Partly cloudy in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. Very hot. High 97°. Heat index up to 108°. UV index up to 8. Wind southwest around 5 mph, gusting to 21 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Rain likely. Scattered thunderstorms likely. Low 75°. Wind south-southwest around 2 mph, gusting to 17 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch.
Thursday	Mostly cloudy to cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 93°. Heat index up to 104°. UV index up to 6. Wind south-southwest around 3 mph, gusting to 18 mph. Chance of precipitation 50 percent. Precipitation mostly around a tenth of an inch.
Thursday night	Fair to partly cloudy. Light to moderate fog after midnight. Low 72°. Wind east-northeast around 7 mph, gusting to 20 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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