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, 27-Jun-2026 04:00 pm

Tonight Rain likely	Sunday Fog a.m. Hot!	Sunday night Fog late	Monday Fog a.m. Hot!	Monday night Fog late	Tuesday Fog a.m. Hot!	Tuesday night Fog late	Wednesday Fog a.m. Hot!
.1 in.
Low: 74°	High: 94°	Low: 74°	High: 96°	Low: 74°	High: 95°	Low: 73°	High: 97°
	Heat: 105°		Heat: 106°		Heat: 106°		Heat: 107°
S 3-19 mph	SSE 6-25→9-26 mph	SSE 7-23 mph	S 9-27 mph	SSW 7-23 mph	SSW 8-26 mph	SSW 5-19 mph	SSW 6-25 mph
	UV: 9 Very High		UV: 10 Very High		UV: 9 Very High		UV: 10 Very High

Tonight	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. Rain likely. Low 74°. Wind south around 3 mph, gusting to 19 mph. Chance of precipitation 60 percent. Precipitation mostly around a tenth of an inch.
Sunday	Sunny. Light to moderate fog in the morning. Hot. High 94°. Heat index up to 105°. UV index up to 9. Wind south-southeast around 6 mph, gusting to 25 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon.
Sunday night	Mostly clear in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 74°. Wind south-southeast around 7 mph, gusting to 23 mph.
Monday	Partly cloudy in the morning, becoming sunny in the afternoon. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 106°. UV index up to 10. Wind south around 9 mph, gusting to 27 mph.
Monday night	Clear in the evening, becoming fair after midnight. Light to moderate fog after midnight. Low 74°. Wind south-southwest around 7 mph, gusting to 23 mph.
Tuesday	Sunny. Light to moderate fog in the morning. Very hot. High 95°. Heat index up to 106°. UV index up to 9. Wind south-southwest around 8 mph, gusting to 26 mph.
Tuesday night	Clear. Light to moderate fog after midnight. Low 73°. Wind south-southwest around 5 mph, gusting to 19 mph.
Wednesday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 97°. Heat index up to 107°. UV index up to 10. Wind south-southwest around 6 mph, gusting to 25 mph.
Wednesday night	Fair to partly cloudy. Patchy light fog after midnight. Low 74°. Wind south-southwest around 5 mph, gusting to 19 mph.
Thursday	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 96°. Heat index up to 106°. UV index up to 9. Wind south-southwest around 5 mph, gusting to 23 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Thursday night	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. Scattered thundershowers possible. Low 74°. Wind south around 4 mph, gusting to 18 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Friday	Sunny in the morning, becoming partly to mostly cloudy in the afternoon. Light to moderate fog in the morning. Hot. High 96°. Heat index up to 106°. UV index up to 9. Wind south around 5 mph, gusting to 24 mph.
Friday night	Partly cloudy. Patchy light fog after midnight. A chance of rain. Scattered thunderstorms likely. Low 74°. Wind west-southwest around 2 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.

WXSIM forecast formatting script by Saratoga-Weather.org.

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