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, 14-Aug-2026 04:00 pm

Tonight Thunder storm	Saturday Rain likely Hot!	Saturday night Thunder storm	Sunday Thunder storm Hot!	Sunday night Thunder storm	Monday Fog a.m.	Monday night Fog late	Tuesday Fog a.m.
<.1 in.	.25 in.	<.1 in.	<.1 in.	.5 in.	<.1 in.
Low: 76°	High: 92°	Low: 76°	High: 92°	Low: 73°	High: 86°	Low: 68°	High: 88°
	Heat: 104°		Heat: 104°				Heat: 94°
S 4-19 mph	SW 6-19 mph	NNW→W 2 mph	WNW 4-18 mph	N 4-18 mph	N 5-22 mph	N 2-19 mph	ESE 2-20 mph
	UV: 8 Very High		UV: 7 High		UV: 6 High		UV: 8 Very High

Tonight	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Warm. Low 76°. Wind south around 4 mph, gusting to 19 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Partly to mostly cloudy in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Rain likely. Precipitation showery or intermittent. Hot. High 92°. Heat index up to 104°. UV index up to 8. Wind southwest around 6 mph, gusting to 19 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.
Saturday night	Partly cloudy. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Scattered thundershowers possible. Low 76°. Wind north-northwest around 2 mph in the evening, becoming west after midnight. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday	Partly to mostly cloudy. Moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 92°. Heat index up to 104°. UV index up to 7. Wind west-northwest around 4 mph, gusting to 18 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Moderate fog. Rain likely in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 73°. Wind north around 4 mph, gusting to 18 mph. Chance of precipitation 80 percent. Precipitation mostly around half an inch.
Monday	Partly cloudy. Moderate fog in the morning. A slight chance of rain in the morning. High 86°. UV index up to 6. Wind north around 5 mph, gusting to 22 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Monday night	Partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Low 68°. Wind north around 2 mph, gusting to 19 mph.
Tuesday	Mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. Hot. High 88°. Heat index up to 94°. UV index up to 8. Wind east-southeast around 2 mph, gusting to 20 mph.
Tuesday night	Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 72°. Wind southeast around 6 mph, gusting to 15 mph.
Wednesday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Hot. High 92°. Heat index up to 98°. UV index up to 8. Wind south around 7 mph, gusting to 22 mph, in the morning, becoming west-northwest in the afternoon.
Wednesday night	Mostly cloudy. Patchy light fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 69°. Wind north around 5 mph, gusting to 19 mph. Chance of precipitation 50 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. Patchy light fog in the morning. A chance of rain. High 81°. UV index up to 7. Wind north around 8 mph, gusting to 28 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Thursday night	Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Patchy light fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 68°. Wind north around 5 mph, gusting to 23 mph. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

Powered by Davis Vantage Pro2 and CumulusMX v 4.6.4 (b4128) MXUI Template v 2.2.6 by Silver Acorn Valid HTML5