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.

Mostly Cloudy

28°F

-2°C

Humidity 63%
Wind Speed NW 15 G 33 mph
Barometer 30.27 in (1025.3 mb)
Dewpoint 17°F (-8°C)
Visibility 10.00 mi
Wind Chill16°F (-9°C)
Last update 30 Nov 4:53 am CST
Extended Forecast for

O'Fallon IL

  • Today

    Today: Partly sunny, with a high near 27. Northwest wind 10 to 18 mph, with gusts as high as 30 mph.

    High: 27 °F

    Partly Sunny

  • Tonight

    Tonight: Cloudy, with a low around 22. Northwest wind 5 to 8 mph becoming calm in the evening.

    Low: 22 °F

    Cloudy

  • Monday

    Monday: A 50 percent chance of snow after noon. Cloudy, with a high near 31. Southeast wind 3 to 6 mph.

    High: 31 °F

    Cloudy then
    Chance Snow

  • Monday Night

    Monday Night: Snow, mainly before midnight. Low around 21. Calm wind becoming northwest around 6 mph after midnight. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.

    Low: 21 °F

    Snow then
    Slight Chance
    Snow

  • Tuesday

    Tuesday: Partly sunny, with a high near 31. Northwest wind around 6 mph becoming light and variable in the afternoon.

    High: 31 °F

    Partly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 19.

    Low: 19 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 39.

    High: 39 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 16.

    Low: 16 °F

    Mostly Cloudy

  • Thursday

    Thursday: Partly sunny, with a high near 23.

    High: 23 °F

    Partly Sunny

Detailed Forecast

Today
Partly sunny, with a high near 27. Northwest wind 10 to 18 mph, with gusts as high as 30 mph.
Tonight
Cloudy, with a low around 22. Northwest wind 5 to 8 mph becoming calm in the evening.
Monday
A 50 percent chance of snow after noon. Cloudy, with a high near 31. Southeast wind 3 to 6 mph.
Monday Night
Snow, mainly before midnight. Low around 21. Calm wind becoming northwest around 6 mph after midnight. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.
Tuesday
Partly sunny, with a high near 31. Northwest wind around 6 mph becoming light and variable in the afternoon.
Tuesday Night
Partly cloudy, with a low around 19.
Wednesday
Mostly sunny, with a high near 39.
Wednesday Night
Mostly cloudy, with a low around 16.
Thursday
Partly sunny, with a high near 23.
Thursday Night
A 20 percent chance of snow after midnight. Mostly cloudy, with a low around 14.
Friday
A 40 percent chance of snow. Mostly cloudy, with a high near 31.
Friday Night
A slight chance of freezing rain. Mostly cloudy, with a low around 24. Chance of precipitation is 20%.
Saturday
Mostly cloudy, with a high near 40.
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:
4:41 am CST Nov 30, 2025
Forecast Valid:
5am CST Nov 30, 2025-6pm CST Dec 6, 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