National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce
Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Fair

72°F

22°C

Humidity 64%
Wind Speed SE 5 mph
Barometer 30.00 in (1015.8 mb)
Dewpoint 59°F (15°C)
Visibility 10.00 mi
Last update 16 Oct 7:53 pm CDT
Extended Forecast for

O'Fallon IL

  • Tonight

    Tonight: Increasing clouds, with a low around 59. Southeast wind around 8 mph, with gusts as high as 20 mph.

    Low: 59 °F

    Increasing
    Clouds

  • Friday

    Friday: Partly sunny, with a high near 83. South wind 6 to 11 mph.

    High: 83 °F

    Partly Sunny

  • Friday Night

    Friday Night: Mostly cloudy, then gradually becoming clear, with a low around 62. South wind 8 to 10 mph.

    Low: 62 °F

    Decreasing
    Clouds

  • Saturday

    Saturday: Showers likely, then showers and possibly a thunderstorm after 10am. High near 82. Southwest wind 9 to 14 mph, with gusts as high as 21 mph. Chance of precipitation is 90%.

    High: 82 °F

    Showers
    Likely then
    Showers

  • Saturday Night

    Saturday Night: Showers and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms between 1am and 4am, then a chance of showers after 4am. Low around 51. Southwest wind 10 to 14 mph becoming west after midnight. Winds could gust as high as 23 mph. Chance of precipitation is 80%.

    Low: 51 °F

    Showers

  • Sunday

    Sunday: Sunny, with a high near 65.

    High: 65 °F

    Sunny

  • Sunday Night

    Sunday Night: Clear, with a low around 45.

    Low: 45 °F

    Clear

  • Monday

    Monday: Sunny, with a high near 73.

    High: 73 °F

    Sunny

  • Monday Night

    Monday Night: A 40 percent chance of showers. Partly cloudy, with a low around 52.

    Low: 52 °F

    Chance
    Showers

Detailed Forecast

Tonight
Increasing clouds, with a low around 59. Southeast wind around 8 mph, with gusts as high as 20 mph.
Friday
Partly sunny, with a high near 83. South wind 6 to 11 mph.
Friday Night
Mostly cloudy, then gradually becoming clear, with a low around 62. South wind 8 to 10 mph.
Saturday
Showers likely, then showers and possibly a thunderstorm after 10am. High near 82. Southwest wind 9 to 14 mph, with gusts as high as 21 mph. Chance of precipitation is 90%.
Saturday Night
Showers and possibly a thunderstorm before 1am, then a chance of showers and thunderstorms between 1am and 4am, then a chance of showers after 4am. Low around 51. Southwest wind 10 to 14 mph becoming west after midnight. Winds could gust as high as 23 mph. Chance of precipitation is 80%.
Sunday
Sunny, with a high near 65.
Sunday Night
Clear, with a low around 45.
Monday
Sunny, with a high near 73.
Monday Night
A 40 percent chance of showers. Partly cloudy, with a low around 52.
Tuesday
A 20 percent chance of showers before 1pm. Sunny, with a high near 65.
Tuesday Night
Mostly clear, with a low around 42.
Wednesday
Sunny, with a high near 66.
Wednesday Night
Partly cloudy, with a low around 46.
Thursday
Mostly sunny, with a high near 67.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
7:26 pm CDT Oct 16, 2025
Forecast Valid:
8pm CDT Oct 16, 2025-6pm CDT Oct 23, 2025
 
Forecast Discussion
 
Get as KML Get as XML

Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

Hourly Weather Forecast

National Digital Forecast Database

National Digital Forecast Database Maximum Temperature Forecast

High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation