O'Fallon, Illinois Weather
your sport, your way
Air Sports Net on FacebookAir Sports Net on Google +Air Sports Net on TwitterReceive RSS UpdatesReceive Email Updates

Click for Hazardous Weather Outlook for O'Fallon, Illinois
Click for Extreme Heat Warning for O'Fallon, Illinois
Change location by the zip code or city,state: or search for other weather forecast locations in Illinois by name.
Weather Forecast for O'Fallon, Illinois : St. Clair County
Issued: 12:36 am CDT Jul 20, 2025 Latitude: 38.5922715 Longitude: -89.9112124 View on Google Maps

MouseOver for Detail Forecast
Overnight Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Cloudy on Overnight Mostly Sunny on Sunday 30% chance of thunderstorms on Monday Mostly Sunny on Tuesday Sunny on Wednesday Sunny on Thursday 20% chance of thunderstorms on Friday 30% chance of thunderstorms on Saturday
Low: 75°F High: 94°F High: 91°F High: 94°F High: 96°F High: 97°F High: 96°F High: 94°F
Low: 75°F Low: 76°F Low: 76°F Low: 77°F Low: 77°F Low: 77°F  
Cloudy Mostly Sunny Thunderstorms Mostly Sunny Sunny Sunny Thunderstorms Thunderstorms
-
Current Conditions at
SCOTT AFB - (KBLV)
79°
Clear
as of 11:55 PM CDST
Rel. Humidity: 94%
Dew Point: 77°F
Visibility: 10 Miles
Pressure: 29.94 in.
Flight Rule: VFR
Wind Data
3 MPH
190° South
Cloud Level(s): Clear
Current Conditions at
EAST ST LOUIS - (KCPS)
79°
Clear
as of 11:53 PM CDST
Rel. Humidity: 88%
Dew Point: 75°F
Visibility: 10 Miles
Pressure: 29.95 in.
Flight Rule: VFR
Wind Data
3 MPH
170° South
Cloud Level(s): Clear
Current Conditions at
ALTON - (KALN)
79°
Clear
as of 12:35 AM CDST
Rel. Humidity: 88%
Dew Point: 75°F
Visibility: 10 Miles
Pressure: 29.95 in.
Flight Rule: VFR
Wind Data
5 MPH
190° South
Cloud Level(s): Clear
Current Conditions at
ST LOUIS - (KSTL)
82°
Mostly Clear
as of 11:51 PM CDST
Rel. Humidity: 83%
Dew Point: 77°F
Visibility: 10 Miles
Pressure: 29.96 in.
Flight Rule: VFR
Wind Data
7 MPH
200° South
Cloud Level(s): Few at 25000ft
Cloudy on Overnight Overnight... Partly cloudy, with a low around 75. Southwest wind around 5 mph.
Mostly Sunny on Sunday Sunday... Mostly sunny, with a high near 94. Heat index values as high as 109. Southwest wind 5 to 7 mph.
40% chance of thunderstorms Sunday Night Sunday Night... A 40 percent chance of showers and thunderstorms, mainly after 7pm. Partly cloudy, with a low around 75. Southwest wind around 5 mph becoming light and variable after midnight.
30% chance of thunderstorms Monday Monday... A 30 percent chance of showers and thunderstorms, mainly after 1pm. Partly sunny, with a high near 91. Heat index values as high as 103. Light and variable wind becoming north around 6 mph in the morning.
Cloudy on Monday Night Monday Night... Partly cloudy, with a low around 76. East wind around 5 mph becoming calm in the evening.
Mostly Sunny on Tuesday Tuesday... Mostly sunny, with a high near 94.
Mostly Clear on Tuesday Night Tuesday Night... Mostly clear, with a low around 76.
Sunny on Wednesday Wednesday... Sunny, with a high near 96.
Mostly Clear on Wednesday Night Wednesday Night... Mostly clear, with a low around 77.
Sunny on Thursday Thursday... Sunny and hot, with a high near 97.
Mostly Clear on Thursday Night Thursday Night... Mostly clear, with a low around 77.
20% chance of thunderstorms Friday Friday... A 20 percent chance of showers and thunderstorms. Sunny, with a high near 96.
Cloudy on Friday Night Friday Night... Partly cloudy, with a low around 77.
30% chance of thunderstorms Saturday Saturday... A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 94.
Current Radar Image


Sun Almanac for O'Fallon, Illinois
Sunrise: 05:52 AM
Sunset: 8:20 PM
Civil Sunrise:05:21 AM
Civil Sunset: 8:51 PM
Nautical Sunrise: 04:44 AM
Nautical Sunset: 9:29 PM
Astro Sunrise: 04:02 AM
Astro Sunset: 10:10 PM
Any use of the information on this page is at your own risk. This information should not be relied upon in life-threatening situations, potential financial loss situations or in lieu of any officially disseminated information. Visit the National Weather Service for official information.