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 05:00 am

Today Chance rain Hot!	Tonight Chance rain	Sunday Chance rain Hot!	Sunday night Chance rain	Monday Fog a.m. Hot!	Monday night Fog late	Tuesday Thunder storm Hot!	Tuesday night Fog late
.1 in.	<.25 in.	<.25 in.	.1 in.			<.1 in.
High: 94°	Low: 77°	High: 90°	Low: 75°	High: 93°	Low: 75°	High: 93°	Low: 71°
Heat: 103°		Heat: 100°		Heat: 103°		Heat: 101°
WSW 8-27 mph	WSW 4-19 mph	NW→NE 3-21 mph	E 3-16 mph	SE→SW 3-20 mph	SW 4-16 mph	W 7-22 mph	NW 5-17 mph
UV: 9 Very High		UV: 9 Very High		UV: 10 Very High		UV: 8 Very High

Today	Partly to mostly sunny. A slight chance of rain in the morning, then a chance of rain in the afternoon. Hot. High 94°. Heat index up to 103°. UV index up to 9. Wind west-southwest around 8 mph, gusting to 27 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Tonight	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Low 77°. Wind west-southwest around 4 mph, gusting to 19 mph. Chance of precipitation 40 percent. Precipitation mostly less than a quarter of an inch.
Sunday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. A chance of rain. High 90°. Heat index up to 100°. UV index up to 9. Wind northwest around 3 mph, gusting to 21 mph, in the morning, becoming northeast in the afternoon. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Sunday night	Fair to partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A chance of rain in the evening, then a slight chance of rain after midnight. Low 75°. Wind east around 3 mph, gusting to 16 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Monday	Partly to mostly sunny in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. Hot. High 93°. Heat index up to 103°. UV index up to 10. Wind southeast around 3 mph, gusting to 20 mph, in the morning, becoming southwest in the afternoon.
Monday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 75°. Wind southwest around 4 mph, gusting to 16 mph.
Tuesday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thundershowers possible. Hot. High 93°. Heat index up to 101°. UV index up to 8. Wind west around 7 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Tuesday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 71°. Wind northwest around 5 mph, gusting to 17 mph.
Wednesday	Partly to mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. High 88°. UV index up to 7. Wind north around 6 mph, gusting to 25 mph.
Wednesday night	Partly cloudy in the evening, becoming fair after midnight. Relatively cool. Low 65°. Wind east-northeast around 5 mph, gusting to 22 mph.
Thursday	Mostly cloudy in the morning, becoming partly cloudy in the afternoon. High 88°. UV index up to 8. Wind southeast around 4 mph, gusting to 23 mph.
Thursday night	Fair in the evening, becoming mostly cloudy after midnight. Relatively cool. Low 67°. Wind southeast around 5 mph, gusting to 20 mph.
Friday	Cloudy. A chance of rain. High 82°. UV index up to 5. Wind southeast around 8 mph, gusting to 25 mph, in the morning, becoming 11 mph, gusting to 28 mph, in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Moderate fog after midnight. A chance of rain. Relatively cool. Low 67°. Wind southeast around 9 mph, gusting to 25 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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