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: Saturday, 18-Jul-2026 04:00 pm

Tonight Rain likely	Sunday Thunder storm Hot!	Sunday night Rain likely	Monday Chance rain	Monday night Fog late	Tuesday Thunder storm Hot!	Tuesday night Fog late	Wednesday Fog a.m.
.1 in.	<.25 in.	<.25 in.	<.1 in.		<.1 in.
Low: 76°	High: 91°	Low: 74°	High: 90°	Low: 74°	High: 94°	Low: 70°	High: 88°
	Heat: 100°		Heat: 99°		Heat: 103°		Heat: 92°
W 4-23 mph	NNE 2-20 mph	E 2 mph	SE→SW 3-16 mph	SSW 4 mph	W→NW 7-21 mph	N 5 mph	NNE 6-25 mph
	UV: 9 Very High		UV: 7 High		UV: 9 Very High		UV: 8 Very High

Tonight	Fair to partly cloudy. Light to moderate fog in the evening, then moderate fog after midnight. Rain likely. Low 76°. Wind west around 4 mph, gusting to 23 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch.
Sunday	Partly cloudy. Light to moderate fog in the morning. Rain likely. Scattered thundershowers possible. High 91°. Heat index up to 100°. UV index up to 9. Wind north-northeast around 2 mph, gusting to 20 mph. Chance of precipitation 70 percent. Precipitation mostly less than a quarter of an inch.
Sunday night	Partly cloudy. Moderate fog. Rain likely. Precipitation showery or intermittent. Low 74°. Wind east around 2 mph. Chance of precipitation 60 percent. Precipitation mostly less than a quarter of an inch.
Monday	Partly cloudy. Moderate fog in the morning. A chance of rain. Precipitation showery or intermittent. High 90°. Heat index up to 99°. UV index up to 7. Wind southeast around 3 mph, gusting to 16 mph, in the morning, becoming southwest in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Monday night	Fair in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 74°. Wind south-southwest around 4 mph.
Tuesday	Sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 94°. Heat index up to 103°. UV index up to 9. Wind west around 7 mph, gusting to 21 mph, in the morning, becoming northwest in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Fair in the evening, becoming clear after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 70°. Wind north around 5 mph.
Wednesday	Mostly sunny. Patchy light fog in the morning. High 88°. Heat index up to 92°. UV index up to 8. Wind north-northeast around 6 mph, gusting to 25 mph.
Wednesday night	Partly cloudy. Relatively cool. Low 67°. Wind east-northeast around 5 mph, gusting to 22 mph.
Thursday	Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. High 89°. UV index up to 9. Wind east around 3 mph, gusting to 23 mph.
Thursday night	Partly cloudy. Relatively cool. Low 67°. Wind east-southeast around 4 mph, gusting to 19 mph.
Friday	Mostly cloudy to cloudy in the morning, becoming sunny in the afternoon. A chance of rain in the morning, then a slight chance of rain in the afternoon. Precipitation showery or intermittent. Hot. High 95°. Heat index up to 99°. UV index up to 9. Wind south around 8 mph, gusting to 24 mph, in the morning, becoming 13 mph, gusting to 30 mph, in the afternoon. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Clear. Low 71°. Wind southwest around 8 mph, gusting to 24 mph, in the evening, becoming 5 mph after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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