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, 08-Aug-2026 05:00 am

Today Mostly Sunny	Tonight Fair	Sunday Mostly Sunny	Sunday night Fog late	Monday Fog a.m. Hot!	Monday night Partly Cloudy	Tuesday Mostly Sunny Hot!	Tuesday night Fog late
		<.1 in.
High: 92°	Low: 69°	High: 91°	Low: 73°	High: 95°	Low: 74°	High: 98°	Low: 74°
Heat: 97°		Heat: 99°		Heat: 106°		Heat: 107°
WSW→S 3-21 mph	SSE 3-15 mph	SSW 7-23 mph	SSW 6-18 mph	SSW 9-26 mph	SSW 7-20 mph	SSW 6-24 mph	SE→S 4-17 mph
UV: 8 Very High		UV: 8 Very High		UV: 8 Very High		UV: 8 Very High

Today	Mostly sunny. Hot. High 92°. Heat index up to 97°. UV index up to 8. Wind west-southwest around 3 mph, gusting to 21 mph, in the morning, becoming south in the afternoon.
Tonight	Fair. Low 69°. Wind south-southeast around 3 mph, gusting to 15 mph.
Sunday	Mostly sunny. A slight chance of rain. Hot. High 91°. Heat index up to 99°. UV index up to 8. Wind south-southwest around 7 mph, gusting to 23 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Sunday night	Fair. Patchy light fog after midnight. Low 73°. Wind south-southwest around 6 mph, gusting to 18 mph.
Monday	Mostly sunny in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Very hot. High 95°. Heat index up to 106°. UV index up to 8. Wind south-southwest around 9 mph, gusting to 26 mph.
Monday night	Partly cloudy. Low 74°. Wind south-southwest around 7 mph, gusting to 20 mph.
Tuesday	Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Very hot. High 98°. Heat index up to 107°. UV index up to 8. Wind south-southwest around 6 mph, gusting to 24 mph.
Tuesday night	Partly cloudy. Patchy light fog after midnight. Low 74°. Wind southeast around 4 mph, gusting to 17 mph, in the evening, becoming south after midnight.
Wednesday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 98°. Heat index up to 109°. UV index up to 8. Wind south around 4 mph, gusting to 22 mph.
Wednesday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 74°. Wind south-southwest around 3 mph, gusting to 18 mph, in the evening, becoming southeast after midnight.
Thursday	Partly to mostly cloudy in the morning, becoming mostly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain. Scattered thundershowers possible. Hot. High 92°. Heat index up to 101°. UV index up to 7. Wind south-southeast around 4 mph, gusting to 21 mph, in the morning, becoming west in the afternoon. Chance of precipitation 40 percent. Precipitation mostly less than a quarter of an inch.
Thursday night	Fair to partly cloudy in the evening, becoming fair after midnight. Light to moderate fog after midnight. Low 70°. Wind north-northwest around 4 mph, gusting to 20 mph.
Friday	Partly to mostly cloudy. Patchy light fog in the morning. High 88°. UV index up to 8. Wind north-northeast around 4 mph, gusting to 23 mph.
Friday night	Cloudy. Patchy light fog after midnight. A slight chance of rain in the evening, then a chance of rain after midnight. Low 68°. Wind northeast around 5 mph, gusting to 19 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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