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

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

25°F

-4°C

Humidity 77%
Wind Speed S 3 mph
Barometer 30.44 in
Dewpoint 19°F (-7°C)
Visibility 10.00 mi
Last update 11 Jan 11:15 pm CST
Extended Forecast for

Williamson IL

  • Tonight

    Tonight: Clear, with a low around 25. Calm wind becoming south 5 to 8 mph after midnight.

    Low: 25 °F

    Clear

  • Monday

    Monday: Sunny, with a high near 48. Southwest wind 7 to 11 mph, with gusts as high as 22 mph.

    High: 48 °F

    Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 34. Southwest wind 6 to 9 mph.

    Low: 34 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Increasing clouds, with a high near 57. Southwest wind 9 to 16 mph, with gusts as high as 28 mph.

    High: 57 °F

    Increasing
    Clouds

  • Tuesday Night

    Tuesday Night: A 20 percent chance of rain before midnight. Mostly cloudy, with a low around 36. West wind 8 to 11 mph, with gusts as high as 20 mph.

    Low: 36 °F

    Slight Chance
    Rain then
    Mostly Cloudy

  • Wednesday

    Wednesday: A slight chance of rain and snow after noon. Mostly cloudy, with a temperature rising to near 40 by 10am, then falling to around 33 during the remainder of the day. Breezy. Chance of precipitation is 20%.

    High: 40 °F⇓

    Breezy.
    Mostly Cloudy
    then Slight
    Chance
    Rain/Snow

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 17. Blustery.

    Low: 17 °F

    Mostly Cloudy
    and Blustery
    then Partly
    Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 32.

    High: 32 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 25.

    Low: 25 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Clear, with a low around 25. Calm wind becoming south 5 to 8 mph after midnight.
Monday
Sunny, with a high near 48. Southwest wind 7 to 11 mph, with gusts as high as 22 mph.
Monday Night
Partly cloudy, with a low around 34. Southwest wind 6 to 9 mph.
Tuesday
Increasing clouds, with a high near 57. Southwest wind 9 to 16 mph, with gusts as high as 28 mph.
Tuesday Night
A 20 percent chance of rain before midnight. Mostly cloudy, with a low around 36. West wind 8 to 11 mph, with gusts as high as 20 mph.
Wednesday
A slight chance of rain and snow after noon. Mostly cloudy, with a temperature rising to near 40 by 10am, then falling to around 33 during the remainder of the day. Breezy. Chance of precipitation is 20%.
Wednesday Night
Mostly cloudy, with a low around 17. Blustery.
Thursday
Mostly sunny, with a high near 32.
Thursday Night
Mostly cloudy, with a low around 25.
Friday
Partly sunny, with a high near 40.
Friday Night
Mostly cloudy, with a low around 21.
Saturday
Mostly cloudy, with a high near 29.
Saturday Night
Partly cloudy, with a low around 13.
Sunday
Mostly sunny, with a high near 29.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Williamson IL
 38.98°N 89.76°W (Elev. 597 ft)
Last Update:
10:36 pm CST Jan 11, 2026
Forecast Valid:
11pm CST Jan 11, 2026-6pm CST Jan 18, 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