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: Thursday, 06-Aug-2026 05:00 am

Today Rain likely	Tonight Chance rain	Friday Chance rain	Friday night Fog	Saturday Fog a.m.	Saturday night Fog late	Sunday Fog a.m. Hot!	Sunday night Fog late
.25 in.	<.25 in.	.1 in.	<.1 in.
High: 86°	Low: 73°	High: 89°	Low: 73°	High: 89°	Low: 73°	High: 93°	Low: 73°
		Heat: 97°		Heat: 97°		Heat: 102°
S 6-23 mph	S 6-19 mph	SW 6-23 mph	WSW 5-20 mph	WNW→ESE 4-21 mph	SE→N 4-16 mph	SW 6-21→9-25 mph	SSW 6-18 mph
UV: 6 High		UV: 8 Very High		UV: 8 Very High		UV: 8 Very High

Today	Mostly cloudy to cloudy in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. Rain likely. Precipitation showery or intermittent. High 86°. UV index up to 6. Wind south around 6 mph, gusting to 23 mph. Chance of precipitation 60 percent. Precipitation mostly around a quarter of an inch.
Tonight	Mostly cloudy. Patchy light fog in the evening, then light to moderate fog after midnight. A chance of rain. Precipitation showery or intermittent. Low 73°. Wind south around 6 mph, gusting to 19 mph. Chance of precipitation 50 percent. Precipitation mostly less than a quarter of an inch.
Friday	Partly to mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Light to moderate fog in the morning. A chance of rain in the morning, then a slight chance of rain in the afternoon. High 89°. Heat index up to 97°. UV index up to 8. Wind southwest around 6 mph, gusting to 23 mph. Chance of precipitation 40 percent. Precipitation mostly around a tenth of an inch.
Friday night	Fair to partly cloudy in the evening, becoming fair after midnight. Moderate fog. A chance of rain. Low 73°. Wind west-southwest around 5 mph, gusting to 20 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Saturday	Partly to mostly sunny in the morning, becoming sunny in the afternoon. Light to moderate fog in the morning. High 89°. Heat index up to 97°. UV index up to 8. Wind west-northwest around 4 mph, gusting to 21 mph, in the morning, becoming east-southeast in the afternoon.
Saturday night	Clear in the evening, becoming partly cloudy after midnight. Patchy light fog in the evening, then light to moderate fog after midnight. Low 73°. Wind southeast around 4 mph, gusting to 16 mph, in the evening, becoming north after midnight.
Sunday	Partly to mostly sunny. Moderate fog in the morning. Hot. High 93°. Heat index up to 102°. UV index up to 8. Wind southwest around 6 mph, gusting to 21 mph, in the morning, becoming 9 mph, gusting to 25 mph, in the afternoon.
Sunday night	Clear. Patchy light fog after midnight. Low 73°. Wind south-southwest around 6 mph, gusting to 18 mph.
Monday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Hot. High 93°. Heat index up to 102°. UV index up to 7. Wind south around 9 mph, gusting to 26 mph.
Monday night	Fair to partly cloudy in the evening, becoming partly cloudy after midnight. Light to moderate fog after midnight. A chance of rain. Low 74°. Wind south around 5 mph, gusting to 18 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Partly cloudy. Patchy light fog in the morning. Hot. High 93°. Heat index up to 103°. UV index up to 7. Wind southwest around 4 mph, gusting to 22 mph, in the morning, becoming 8 mph, gusting to 25 mph, in the afternoon.
Tuesday night	Partly cloudy in the evening, becoming fair to partly cloudy after midnight. Patchy light fog after midnight. A slight chance of rain. Scattered thundershowers possible. Low 75°. Wind south-southwest around 2 mph, gusting to 16 mph, in the evening, becoming east after midnight. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Wednesday	Mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. A slight chance of rain. Precipitation showery or intermittent. Hot. High 90°. Heat index up to 100°. UV index up to 8. Wind south-southeast around 5 mph, gusting to 21 mph, in the morning, becoming 9 mph, gusting to 26 mph, in the afternoon. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Wednesday night	Partly cloudy. Patchy light fog after midnight. Low 75°. Wind south-southeast around 7 mph, gusting to 22 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

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