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

Hazardous Weather Conditions

Current conditions at

St. Louis Downtown Airport (KCPS)

Lat: 38.56°NLon: 90.15°WElev: 410ft.

Overcast

58°F

14°C

Humidity 93%
Wind Speed S 3 mph
Barometer 29.77 in (1008.0 mb)
Dewpoint 56°F (13°C)
Visibility 10.00 mi
Last update 9 May 12:53 am CDT
Extended Forecast for

O'Fallon IL

  • Overnight

    Overnight: Scattered showers and thunderstorms before 1am. Patchy fog between 3am and 4am. Otherwise, cloudy early, then gradual clearing, with a low around 54. Light and variable wind. Chance of precipitation is 30%.

    Low: 54 °F

    Scattered
    Showers and
    Patchy Fog

  • Saturday

    Saturday: Partly sunny, then gradually becoming sunny, with a high near 80. West wind 5 to 11 mph.

    High: 80 °F

    Becoming
    Sunny

  • Saturday Night

    Saturday Night: A slight chance of showers and thunderstorms before 1am, then a slight chance of showers between 1am and 2am. Increasing clouds, with a low around 57. Light and variable wind becoming north 5 to 7 mph after midnight. Chance of precipitation is 20%.

    Low: 57 °F

    Slight Chance
    T-storms

  • Sunday

    Sunday: Partly sunny, with a high near 68. North wind 8 to 10 mph.

    High: 68 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 45. North wind 3 to 7 mph.

    Low: 45 °F

    Partly Cloudy

  • Monday

    Monday: Sunny, with a high near 70.

    High: 70 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 49.

    Low: 49 °F

    Mostly Clear

  • Tuesday

    Tuesday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 77.

    High: 77 °F

    Sunny then
    Slight Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 58.

    Low: 58 °F

    Slight Chance
    T-storms

Detailed Forecast

Overnight
Scattered showers and thunderstorms before 1am. Patchy fog between 3am and 4am. Otherwise, cloudy early, then gradual clearing, with a low around 54. Light and variable wind. Chance of precipitation is 30%.
Saturday
Partly sunny, then gradually becoming sunny, with a high near 80. West wind 5 to 11 mph.
Saturday Night
A slight chance of showers and thunderstorms before 1am, then a slight chance of showers between 1am and 2am. Increasing clouds, with a low around 57. Light and variable wind becoming north 5 to 7 mph after midnight. Chance of precipitation is 20%.
Sunday
Partly sunny, with a high near 68. North wind 8 to 10 mph.
Sunday Night
Partly cloudy, with a low around 45. North wind 3 to 7 mph.
Monday
Sunny, with a high near 70.
Monday Night
Mostly clear, with a low around 49.
Tuesday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 77.
Tuesday Night
A 20 percent chance of showers and thunderstorms before 1am. Mostly clear, with a low around 58.
Wednesday
Sunny, with a high near 76.
Wednesday Night
Mostly clear, with a low around 52.
Thursday
Sunny, with a high near 77.
Thursday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 59.
Friday
A 20 percent chance of showers and thunderstorms. Partly sunny, with a high near 84.
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:
12:21 am CDT May 9, 2026
Forecast Valid:
12am CDT May 9, 2026-6pm CDT May 15, 2026
 
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