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.

Partly Cloudy

20°F

-7°C

Humidity 65%
Wind Speed NE 12 mph
Barometer 30.44 in (1031.3 mb)
Dewpoint 10°F (-12°C)
Visibility 10.00 mi
Wind Chill8°F (-13°C)
Last update 4 Dec 9:53 am CST
Extended Forecast for

O'Fallon IL

  • Today

    Today: Partly sunny, with a high near 24. North wind 5 to 8 mph.

    High: 24 °F

    Partly Sunny

  • Tonight

    Tonight: Mostly cloudy, then gradually becoming mostly clear, with a low around 12. North wind around 5 mph becoming calm in the evening.

    Low: 12 °F

    Decreasing
    Clouds

  • Friday

    Friday: Sunny, with a high near 38. Calm wind becoming south 5 to 7 mph in the morning.

    High: 38 °F

    Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 26. South wind around 6 mph becoming light and variable after midnight.

    Low: 26 °F

    Mostly Cloudy

  • Saturday

    Saturday: Partly sunny, with a high near 38. Light and variable wind becoming northeast around 6 mph in the afternoon.

    High: 38 °F

    Partly Sunny

  • Saturday Night

    Saturday Night: A chance of freezing rain after midnight. Cloudy, with a low around 28. Chance of precipitation is 30%.

    Low: 28 °F

    Mostly Cloudy
    then Chance
    Freezing Rain

  • Sunday

    Sunday: A slight chance of rain and snow before noon. Mostly cloudy, with a high near 34. Chance of precipitation is 20%.

    High: 34 °F

    Slight Chance
    Rain/Snow
    then Mostly
    Cloudy

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 18.

    Low: 18 °F

    Mostly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 32.

    High: 32 °F

    Mostly Sunny

Detailed Forecast

Today
Partly sunny, with a high near 24. North wind 5 to 8 mph.
Tonight
Mostly cloudy, then gradually becoming mostly clear, with a low around 12. North wind around 5 mph becoming calm in the evening.
Friday
Sunny, with a high near 38. Calm wind becoming south 5 to 7 mph in the morning.
Friday Night
Mostly cloudy, with a low around 26. South wind around 6 mph becoming light and variable after midnight.
Saturday
Partly sunny, with a high near 38. Light and variable wind becoming northeast around 6 mph in the afternoon.
Saturday Night
A chance of freezing rain after midnight. Cloudy, with a low around 28. Chance of precipitation is 30%.
Sunday
A slight chance of rain and snow before noon. Mostly cloudy, with a high near 34. Chance of precipitation is 20%.
Sunday Night
Mostly cloudy, with a low around 18.
Monday
Mostly sunny, with a high near 32.
Monday Night
Partly cloudy, with a low around 23.
Tuesday
Partly sunny, with a high near 44.
Tuesday Night
Mostly cloudy, with a low around 32.
Wednesday
A 20 percent chance of rain. Mostly cloudy, with a high near 47.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
O'Fallon IL
 38.59°N 89.92°W (Elev. 551 ft)
Last Update:
7:31 am CST Dec 4, 2025
Forecast Valid:
10am CST Dec 4, 2025-6pm CST Dec 10, 2025
 
Forecast Discussion
 
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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