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, 18-Aug-2026 04:00 pm

Tonight Thunder storm	Wednesday Thunder storm	Wednesday night Thunder storm	Thursday Fog a.m.	Thursday night Fog late	Friday Fog a.m.	Friday night Fog late	Saturday Fog a.m.
.35 in.	.25 in.	<.25 in.	<.1 in.
Low: 72°	High: 83°	Low: 71°	High: 84°	Low: 67°	High: 87°	Low: 69°	High: 86°

E 3-21 mph	SE→ENE 2-19 mph	ENE 3-17 mph	NE 4-23 mph	NE→E 2-18 mph	S→SW 2-19 mph	WNW calm	NW 7-25 mph
	UV: 5 Medium		UV: 7 High		UV: 7 High		UV: 7 High

Tonight	Fair to partly cloudy in the evening, becoming mostly cloudy after midnight. Moderate fog after midnight. A slight chance of rain in the evening, then rain likely after midnight. Scattered thundershowers possible. Low 72°. Wind east around 3 mph, gusting to 21 mph. Chance of precipitation 60 percent. Precipitation mostly between a quarter and half an inch.
Wednesday	Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely. Scattered thunderstorms likely. High 83°. UV index up to 5. Wind southeast around 2 mph, gusting to 19 mph, in the morning, becoming east-northeast in the afternoon. Chance of precipitation 70 percent. Precipitation mostly around a quarter of an inch.
Wednesday night	Fair to partly 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. Scattered thundershowers possible. Low 71°. Wind east-northeast around 3 mph, gusting to 17 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Thursday	Partly to mostly sunny. Moderate fog in the morning. A chance of rain. High 84°. UV index up to 7. Wind northeast around 4 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Thursday night	Clear in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Low 67°. Wind northeast around 2 mph, gusting to 18 mph, in the evening, becoming east after midnight.
Friday	Sunny in the morning, becoming mostly sunny in the afternoon. Patchy light fog in the morning. High 87°. UV index up to 7. Wind south around 2 mph, gusting to 19 mph, in the morning, becoming southwest in the afternoon.
Friday night	Fair in the evening, becoming clear after midnight. Light to moderate fog after midnight. Low 69°. Wind west-northwest near calm.
Saturday	Mostly sunny. Light to moderate fog in the morning. High 86°. UV index up to 7. Wind northwest around 7 mph, gusting to 25 mph.
Saturday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 66°. Wind north around 4 mph, gusting to 18 mph.
Sunday	Partly cloudy. Patchy light fog in the morning. High 85°. UV index up to 8. Wind north around 3 mph, gusting to 21 mph.
Sunday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 64°. Wind east-northeast around 3 mph, gusting to 17 mph.
Monday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. High 87°. UV index up to 8. Wind east-southeast around 6 mph, gusting to 23 mph.
Monday night	Fair in the evening, becoming mostly cloudy to cloudy after midnight. Low 66°. Wind east-southeast around 5 mph, gusting to 20 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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