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: Wednesday, 16-Sep-2026 04:00 pm

Tonight Fog late	Thursday Fog a.m. Hot!	Thursday night Fog late	Friday Fog a.m.	Friday night Partly Cloudy	Saturday Fog a.m. Hot!	Saturday night Partly Cloudy	Sunday Partly Cloudy
<.1 in.
Low: 73°	High: 96°	Low: 70°	High: 93°	Low: 69°	High: 94°	Low: 69°	High: 93°
	Heat: 106°		Heat: 99°		Heat: 100°		Heat: 97°
S 3-17 mph	SW 5-23 mph	WSW→NNE calm	ENE→SSE 3-20 mph	SSE 4 mph	SSW 5-20 mph	S→SW 2 mph	N→NW 3-21 mph
	UV: 7 High		UV: 6 High		UV: 6 High		UV: 7 High

Tonight	Partly cloudy in the evening, becoming fair after midnight. Patchy light fog in the evening, then moderate fog after midnight. A slight chance of rain. Warm. Low 73°. Wind south around 3 mph, gusting to 17 mph. Chance of precipitation 20 percent. Precipitation mostly less than a tenth of an inch.
Thursday	Mostly sunny. Moderate fog in the morning. Extremely hot. High 96°. Heat index up to 106°. UV index up to 7. Wind southwest around 5 mph, gusting to 23 mph.
Thursday night	Fair in the evening, becoming clear after midnight. Patchy light fog after midnight. Warm. Low 70°. Wind west-southwest near calm in the evening, becoming north-northeast after midnight.
Friday	Sunny in the morning, becoming partly to mostly sunny in the afternoon. Patchy light fog in the morning. Very hot. High 93°. Heat index up to 99°. UV index up to 6. Wind east-northeast around 3 mph, gusting to 20 mph, in the morning, becoming south-southeast in the afternoon.
Friday night	Fair in the evening, becoming partly cloudy after midnight. Warm. Low 69°. Wind south-southeast around 4 mph.
Saturday	Partly cloudy. Light to moderate fog in the morning. Very hot. High 94°. Heat index up to 100°. UV index up to 6. Wind south-southwest around 5 mph, gusting to 20 mph.
Saturday night	Partly cloudy. Warm. Low 69°. Wind south around 2 mph in the evening, becoming southwest after midnight.
Sunday	Partly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Very hot. High 93°. Heat index up to 97°. UV index up to 7. Wind north around 3 mph, gusting to 21 mph, in the morning, becoming northwest in the afternoon.
Sunday night	Partly cloudy in the evening, becoming partly to mostly cloudy after midnight. Low 65°. Wind north-northeast around 4 mph.
Monday	Mostly cloudy in the morning, becoming partly to mostly sunny in the afternoon. Moderate fog in the afternoon. A slight chance of rain in the morning, then rain likely in the afternoon. Warm. High 83°. UV index up to 7. Wind north-northeast around 5 mph, gusting to 23 mph, in the morning, becoming northwest in the afternoon. Chance of precipitation 70 percent. Precipitation mostly around half an inch.
Monday night	Moderate fog. A chance of rain in the evening, then a slight chance of rain after midnight. Low 61°. Wind north around 6 mph, gusting to 15 mph. Chance of precipitation 30 percent. Precipitation mostly less than a tenth of an inch.
Tuesday	Partly to mostly sunny in the morning, becoming mostly cloudy in the afternoon. Light to moderate fog in the morning. High 78°. UV index up to 4. Wind north-northwest around 6 mph, gusting to 23 mph.
Tuesday night	Fair to partly cloudy in the evening, becoming clear after midnight. Light to moderate fog after midnight. Low 55°. Wind north around 5 mph, gusting to 16 mph.

WXSIM forecast formatting script by Saratoga-Weather.org.

Powered by Davis Vantage Pro2 and CumulusMX v 4.6.4 (b4128) MXUI Template v 2.2.6 by Silver Acorn Valid HTML5