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, 25-Jul-2026 05:00 am

Today Thunder storm	Tonight Thunder storm	Sunday Chance rain Hot!	Sunday night Fog late	Monday Fog a.m. Hot!	Monday night Partly Cloudy	Tuesday Mostly Sunny Hot!	Tuesday night Partly Cloudy
<.25 in.	.1 in.	<.1 in.
High: 88°	Low: 73°	High: 92°	Low: 75°	High: 95°	Low: 74°	High: 95°	Low: 70°
Heat: 94°		Heat: 103°		Heat: 108°		Heat: 103°
SW 6-23 mph	SW 2 mph	NW→SSW 3-20 mph	SSW 3 mph	SW 6-20→10-24 mph	W 6-18 mph	NW 8-26 mph	NE 4-21 mph
UV: 9 Very High		UV: 9 Very High		UV: 9 Very High		UV: 9 Very High

Today	Mostly cloudy in the morning, becoming partly cloudy in the afternoon. A chance of rain. Scattered thundershowers possible. High 88°. Heat index up to 94°. UV index up to 9. Wind southwest around 6 mph, gusting to 23 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Tonight	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 73°. Wind southwest around 2 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Sunday	Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. A chance of rain. Hot. High 92°. Heat index up to 103°. UV index up to 9. Wind northwest around 3 mph, gusting to 20 mph, in the morning, becoming south-southwest in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Partly cloudy. Light to moderate fog after midnight. Low 75°. Wind south-southwest around 3 mph.
Monday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Hot. High 95°. Heat index up to 108°. UV index up to 9. Wind southwest around 6 mph, gusting to 20 mph, in the morning, becoming 10 mph, gusting to 24 mph, in the afternoon.
Monday night	Clear in the evening, becoming fair to partly cloudy after midnight. Low 74°. Wind west around 6 mph, gusting to 18 mph.
Tuesday	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Hot. High 95°. Heat index up to 103°. UV index up to 9. Wind northwest around 8 mph, gusting to 26 mph.
Tuesday night	Clear in the evening, becoming fair to partly cloudy after midnight. Low 70°. Wind northeast around 4 mph, gusting to 21 mph.
Wednesday	Partly cloudy. Hot. High 90°. Heat index up to 95°. UV index up to 7. Wind northeast around 2 mph, gusting to 22 mph, in the morning, becoming 6 mph, gusting to 23 mph, in the afternoon.
Wednesday night	Clear in the evening, becoming mostly clear after midnight. Patchy light fog after midnight. Low 68°. Wind northeast around 4 mph, gusting to 19 mph.
Thursday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. Hot. High 90°. Heat index up to 94°. UV index up to 8. Wind east-northeast around 5 mph, gusting to 23 mph.
Thursday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Relatively cool. Low 67°. Wind east around 4 mph, gusting to 21 mph.
Friday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Hot. High 94°. UV index up to 9. Wind south around 4 mph, gusting to 23 mph, in the morning, becoming southeast around 7 mph, gusting to 23 mph, in the afternoon.
Friday night	Partly cloudy in the evening, becoming mostly cloudy after midnight. Low 71°. Wind southeast around 5 mph, gusting to 21 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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