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, 13-Jun-2026 05:00 am

Today Thunder storm	Tonight Thunder storm	Sunday Thunder storm	Sunday night Partly Cloudy	Monday Partly Cloudy	Monday night Fog late	Tuesday Thunder storm	Tuesday night Fog late
.25 in.	.5 in.	<.1 in.				<.25 in.
High: 84°	Low: 69°	High: 80°	Low: 61°	High: 79°	Low: 60°	High: 82°	Low: 66°

S 6-24 mph	S→WNW 5-21 mph	N 10-29 mph	N 4-26 mph	W 4-23 mph	SW 5-20 mph	SSW 8-27 mph	SW 8-23→5 mph
UV: 8 Very High		UV: 9 Very High		UV: 7 High		UV: 8 Very High

Today	Mostly cloudy to cloudy in the morning, becoming partly cloudy in the afternoon. A chance of rain. Scattered thunderstorms likely. High 84°. UV index up to 8. Wind south around 6 mph, gusting to 24 mph. Chance of precipitation 50 percent. Precipitation mostly around a quarter of an inch.
Tonight	Mostly cloudy to cloudy in the evening, becoming cloudy after midnight. Light to moderate fog. Rain likely in the evening, then a chance of rain after midnight. Thunderstorms very likely, some possibly severe. Low 69°. Wind south around 5 mph, gusting to 21 mph, in the evening, becoming west-northwest after midnight. Chance of precipitation 80 percent. Precipitation mostly around half an inch.
Sunday	Mostly cloudy in the morning, becoming mostly sunny in the afternoon. Light to moderate fog in the morning. A slight chance of rain. Scattered thunderstorms likely, some possibly severe. High 80°. UV index up to 9. Wind north around 10 mph, gusting to 29 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Relatively cool. Low 61°. Wind north around 4 mph, gusting to 26 mph.
Monday	Mostly sunny in the morning, becoming partly cloudy in the afternoon. High 79°. UV index up to 7. Wind west around 4 mph, gusting to 23 mph.
Monday night	Fair to partly cloudy in the evening, becoming clear after midnight. Light to moderate fog after midnight. Relatively cool. Low 60°. Wind southwest around 5 mph, gusting to 20 mph.
Tuesday	Partly to mostly sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Scattered thunderstorms likely. High 82°. UV index up to 8. Wind south-southwest around 8 mph, gusting to 27 mph. Chance of precipitation 40 percent. Precipitation mostly less than a quarter of an inch.
Tuesday night	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 66°. Wind southwest around 8 mph, gusting to 23 mph, in the evening, becoming 5 mph after midnight.
Wednesday	Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. A slight chance of rain in the morning, then a chance of rain in the afternoon. Thunderstorms very likely, some possibly severe. High 88°. Heat index up to 93°. UV index up to 7. Wind south-southwest around 8 mph, gusting to 27 mph, in the morning, becoming 13 mph, gusting to 28 mph, in the afternoon. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Wednesday night	Partly to mostly cloudy in the evening, becoming mostly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Rain very likely. Thunderstorms very likely, some severe. Low 69°. Wind west-southwest around 13 mph, gusting to 26 mph, in the evening, becoming 9 mph, gusting to 16 mph, after midnight. Chance of precipitation 80 percent. Precipitation mostly around an inch.
Thursday	Partly cloudy in the morning, becoming partly to mostly cloudy in the afternoon. Moderate fog in the morning. Rain likely in the morning, then a chance of rain in the afternoon. Precipitation showery or intermittent. High 79°. UV index up to 8. Wind northwest around 6 mph, gusting to 21 mph. Chance of precipitation 70 percent. Precipitation mostly around half an inch.
Thursday night	Fair in the evening, becoming fair to partly cloudy after midnight. Light to moderate fog in the evening, then moderate fog after midnight. Low 65°. Wind northwest around 5 mph, gusting to 19 mph.
Friday	Cloudy. Patchy light fog in the morning. High 75°. UV index up to 5. Wind northwest around 7 mph, gusting to 23 mph.
Friday night	Cloudy in the evening, becoming mostly cloudy after midnight. Low 65°. Wind northeast around 2 mph, gusting to 19 mph.

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