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 05:00 am

Today Mostly Sunny Hot!	Tonight Partly Cloudy	Monday Partly Cloudy Hot!	Monday night Fog late	Tuesday Fog a.m. Hot!	Tuesday night Fog late	Wednesday Mostly Sunny Hot!	Wednesday night Fog late

High: 93°	Low: 71°	High: 96°	Low: 73°	High: 97°	Low: 73°	High: 97°	Low: 73°
Heat: 101°		Heat: 104°		Heat: 107°		Heat: 107°
S 5-26→9-26 mph	SSW 7-22 mph	SSW 8-27 mph	SSW 7-23 mph	SSW 8-26 mph	SSW 5-21 mph	SSW 6-25 mph	SSE 5-20 mph
UV: 9 Very High		UV: 10 Very High		UV: 9 Very High		UV: 9 Very High

Today	Mostly sunny in the morning, becoming sunny in the afternoon. Hot. High 93°. Heat index up to 101°. UV index up to 9. Wind south around 5 mph, gusting to 26 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon.
Tonight	Fair in the evening, becoming partly cloudy after midnight. Low 71°. Wind south-southwest around 7 mph, gusting to 22 mph.
Monday	Partly cloudy. Hot. High 96°. Heat index up to 104°. UV index up to 10. Wind south-southwest around 8 mph, gusting to 27 mph.
Monday night	Fair to partly cloudy. Patchy light fog after midnight. Low 73°. Wind south-southwest around 7 mph, gusting to 23 mph.
Tuesday	Sunny. Patchy light fog in the morning. Very hot. High 97°. Heat index up to 107°. UV index up to 9. Wind south-southwest around 8 mph, gusting to 26 mph.
Tuesday night	Clear. Patchy light fog after midnight. Low 73°. Wind south-southwest around 5 mph, gusting to 21 mph.
Wednesday	Sunny in the morning, becoming mostly sunny in the afternoon. Very hot. High 97°. Heat index up to 107°. UV index up to 9. Wind south-southwest around 6 mph, gusting to 25 mph.
Wednesday night	Fair to partly cloudy in the evening, becoming mostly clear after midnight. Light to moderate fog after midnight. Low 73°. Wind south-southeast around 5 mph, gusting to 20 mph.
Thursday	Mostly sunny in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. A chance of rain in the afternoon. Scattered thunderstorms likely. Hot. High 95°. Heat index up to 105°. UV index up to 10. Wind south-southwest around 6 mph, gusting to 25 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Thursday night	Partly cloudy. Moderate fog. A chance of rain in the evening, then a slight chance of rain after midnight. Scattered thundershowers possible. Low 76°. Wind south-southwest around 5 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Friday	Mostly sunny in the morning, becoming partly to mostly cloudy in the afternoon. Moderate fog in the morning. A slight chance of rain. Scattered thunderstorms likely, some possibly severe. Hot. High 93°. Heat index up to 104°. UV index up to 7. Wind south-southwest around 6 mph, gusting to 22 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Friday night	Partly cloudy in the evening, becoming clear after midnight. Light to moderate fog in the evening, then moderate fog after midnight. A slight chance of rain. Scattered thunderstorms likely. Low 75°. Wind south-southeast around 4 mph, gusting to 17 mph, in the evening, becoming southwest after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Sunny in the morning, becoming mostly sunny in the afternoon. Moderate fog in the morning. Hot. High 95°. Heat index up to 106°. UV index up to 9. Wind southwest around 4 mph, gusting to 21 mph.
Saturday night	Partly cloudy in the evening, becoming mostly clear after midnight. Patchy light fog in the evening, then moderate fog after midnight. Low 74°. Wind east-southeast around 3 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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