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: Sunday, 28-Jun-2026 04:00 pm

Tonight 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!	Wednesday night Fog late	Thursday Thunder storm Hot!
							.1 in.
Low: 75°	High: 97°	Low: 73°	High: 99°	Low: 74°	High: 100°	Low: 74°	High: 98°
	Heat: 107°		Heat: 109°		Heat: 111°		Heat: 110°
S 6-26 mph	S 8-27 mph	S 7-23 mph	SSW 7-26 mph	SSW 5-20 mph	SSW 6-25 mph	S 4-21 mph	SSW 5-23 mph
	UV: 10 Very High		UV: 10 Very High		UV: 9 Very High		UV: 10 Very High

Tonight	Mostly clear in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 75°. Wind south around 6 mph, gusting to 26 mph.
Monday	Partly cloudy 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 around 8 mph, gusting to 27 mph.
Monday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. Low 73°. Wind south around 7 mph, gusting to 23 mph.
Tuesday	Sunny. Patchy light fog in the morning. Very hot. High 99°. Heat index up to 109°. UV index up to 10. Wind south-southwest around 7 mph, gusting to 26 mph.
Tuesday night	Clear. Patchy light fog after midnight. Low 74°. Wind south-southwest around 5 mph, gusting to 20 mph.
Wednesday	Sunny. Patchy light fog in the morning. Very hot. High 100°. Heat index up to 111°. UV index up to 9. Wind south-southwest around 6 mph, gusting to 25 mph.
Wednesday night	Fair in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 74°. Wind south around 4 mph, gusting to 21 mph.
Thursday	Sunny in the morning, becoming partly cloudy in the afternoon. Patchy light fog in the morning. A chance of rain in the afternoon. Thunderstorms very likely, some possibly severe. Very hot. High 98°. Heat index up to 110°. UV index up to 10. Wind south-southwest around 5 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Thursday night	Partly cloudy in the evening, becoming mostly clear after midnight. Moderate fog. A chance of rain. Scattered thunderstorms likely. Low 76°. Wind southeast around 6 mph, gusting to 16 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Friday	Sunny in the morning, becoming partly cloudy in the afternoon. Moderate fog in the morning. Hot. High 96°. Heat index up to 109°. UV index up to 7. Wind south-southwest around 5 mph, gusting to 22 mph.
Friday night	Partly cloudy in the evening, becoming clear after midnight. Moderate fog after midnight. Low 74°. Wind southeast around 4 mph, gusting to 16 mph, in the evening, becoming south-southwest after midnight.
Saturday	Sunny in the morning, becoming partly cloudy in the afternoon. Light to moderate fog in the morning. Very hot. High 97°. Heat index up to 108°. UV index up to 9. Wind south-southwest around 4 mph, gusting to 22 mph.
Saturday night	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog after midnight. Low 72°. Wind south-southeast around 4 mph in the evening, becoming south-southwest after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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