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 05:00 am

Today Chance rain	Tonight Chance rain	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
<.1 in.	<.25 in.
High: 88°	Low: 73°	High: 94°	Low: 73°	High: 96°	Low: 73°	High: 97°	Low: 73°
Heat: 92°		Heat: 104°		Heat: 106°		Heat: 107°
SSW 3-22 mph	SSE 4-20 mph	SSE→SSW 7-26 mph	SSW 6-22 mph	SSW 8-26 mph	SSW 7-21 mph	SSW 6-25 mph	SSW 5-19 mph
UV: 6 High		UV: 9 Very High		UV: 10 Very High		UV: 9 Very High

Today	Mostly cloudy. A slight chance of rain in the morning, then a chance of rain in the afternoon. High 88°. Heat index up to 92°. UV index up to 6. Wind south-southwest around 3 mph, gusting to 22 mph. Chance of precipitation 40 percent. Precipitation mostly less than a tenth of an inch.
Tonight	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog in the evening, then moderate fog after midnight. A chance of rain. Low 73°. Wind south-southeast around 4 mph, gusting to 20 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Sunday	Sunny. Patchy light fog in the morning. Hot. High 94°. Heat index up to 104°. UV index up to 9. Wind south-southeast around 7 mph, gusting to 26 mph, in the morning, becoming south-southwest in the afternoon.
Sunday night	Partly cloudy. Patchy light fog after midnight. Low 73°. Wind south-southwest around 6 mph, gusting to 22 mph.
Monday	Partly to mostly sunny. Patchy light fog in the morning. Very hot. High 96°. Heat index up to 106°. UV index up to 10. Wind south-southwest around 8 mph, gusting to 26 mph.
Monday night	Partly cloudy in the evening, becoming clear after midnight. Patchy light fog after midnight. Low 73°. Wind south-southwest around 7 mph, gusting to 21 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 6 mph, gusting to 25 mph.
Tuesday night	Clear. Patchy light 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 9. Wind south around 5 mph, gusting to 23 mph.
Wednesday night	Partly to mostly cloudy in the evening, becoming partly cloudy after midnight. Patchy light fog after midnight. Low 74°. Wind south around 4 mph, gusting to 18 mph.
Thursday	Partly cloudy. Patchy light fog in the morning. A slight chance of rain. Scattered thundershowers possible. Hot. High 94°. Heat index up to 105°. UV index up to 10. Wind south around 5 mph, gusting to 24 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Thursday night	Fair to partly cloudy in the evening, becoming clear after midnight. Moderate fog. Low 74°. Wind south-southwest around 4 mph, gusting to 17 mph.
Friday	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 10. Wind southwest around 4 mph, gusting to 22 mph.
Friday night	Partly cloudy in the evening, becoming mostly clear after midnight. Moderate fog after midnight. Low 74°. Wind southeast around 3 mph in the evening, becoming west after midnight.

WXSIM forecast formatting script by Saratoga-Weather.org.

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