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

41°F

5°C

Humidity 57%
Wind Speed S 8 mph
Barometer 30.12 in
Dewpoint 27°F (-3°C)
Visibility 10.00 mi
Wind Chill36°F (2°C)
Last update 12 Jan 8:50 pm CST
Extended Forecast for

Alton IL

  • Tonight

    Tonight: Increasing clouds, with a low around 36. South wind 3 to 8 mph.

    Low: 36 °F

    Increasing
    Clouds

  • Tuesday

    Tuesday: Increasing clouds, with a high near 59. West wind 9 to 15 mph, with gusts as high as 29 mph.

    High: 59 °F

    Increasing
    Clouds

  • Tuesday Night

    Tuesday Night: A 30 percent chance of rain, mainly before 11pm. Cloudy, then gradually becoming partly cloudy, with a low around 36. West wind 9 to 14 mph, with gusts as high as 22 mph.

    Low: 36 °F

    Chance Rain
    then Mostly
    Cloudy

  • Wednesday

    Wednesday: Mostly cloudy, with a temperature rising to near 40 by 11am, then falling to around 32 during the remainder of the day. Breezy, with a northwest wind 15 to 22 mph, with gusts as high as 33 mph.

    High: 40 °F⇓

    Mostly Cloudy
    and Breezy

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 17. North wind 9 to 16 mph, with gusts as high as 24 mph.

    Low: 17 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 31.

    High: 31 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 24.

    Low: 24 °F

    Mostly Cloudy

  • Friday

    Friday: A 20 percent chance of snow after noon. Mostly cloudy, with a high near 41.

    High: 41 °F

    Mostly Cloudy
    then Slight
    Chance Snow

  • Friday Night

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

    Low: 18 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Increasing clouds, with a low around 36. South wind 3 to 8 mph.
Tuesday
Increasing clouds, with a high near 59. West wind 9 to 15 mph, with gusts as high as 29 mph.
Tuesday Night
A 30 percent chance of rain, mainly before 11pm. Cloudy, then gradually becoming partly cloudy, with a low around 36. West wind 9 to 14 mph, with gusts as high as 22 mph.
Wednesday
Mostly cloudy, with a temperature rising to near 40 by 11am, then falling to around 32 during the remainder of the day. Breezy, with a northwest wind 15 to 22 mph, with gusts as high as 33 mph.
Wednesday Night
Mostly clear, with a low around 17. North wind 9 to 16 mph, with gusts as high as 24 mph.
Thursday
Mostly sunny, with a high near 31.
Thursday Night
Mostly cloudy, with a low around 24.
Friday
A 20 percent chance of snow after noon. Mostly cloudy, with a high near 41.
Friday Night
Mostly cloudy, with a low around 18.
Saturday
Mostly cloudy, with a high near 27.
Saturday Night
Partly cloudy, with a low around 9.
Sunday
Mostly sunny, with a high near 25.
Sunday Night
Partly cloudy, with a low around 13.
M.L.King Day
Mostly sunny, with a high near 34.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.93°N 90.16°W (Elev. 505 ft)
Last Update:
9:41 pm CST Jan 12, 2026
Forecast Valid:
9pm CST Jan 12, 2026-6pm CST Jan 19, 2026
 
Forecast Discussion
 
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Additional Resources

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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