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

51°F

11°C

Humidity 44%
Wind Speed SE 6 mph
Barometer 30.15 in
Dewpoint 29°F (-2°C)
Visibility 10.00 mi
Wind Chill49°F (9°C)
Last update 25 Mar 1:35 am CDT
Extended Forecast for

Alton IL

  • Overnight

    Overnight: Partly cloudy, with a low around 43. Southeast wind around 6 mph.

    Low: 43 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 77. Southeast wind 5 to 11 mph becoming south in the afternoon.

    High: 77 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A slight chance of showers and thunderstorms between 11pm and midnight. Mostly cloudy, then gradually becoming clear, with a low around 64. South wind around 10 mph. Chance of precipitation is 20%.

    Low: 64 °F

    Slight Chance
    T-storms then
    Mostly Clear

  • Thursday

    Thursday: A 20 percent chance of rain after 1pm. Sunny, with a high near 90. Southwest wind 9 to 14 mph, with gusts as high as 26 mph.

    High: 90 °F

    Sunny then
    Slight Chance
    Rain

  • Thursday Night

    Thursday Night: Showers and possibly a thunderstorm before 4am, then rain after 4am. Low around 43. Southwest wind 9 to 17 mph becoming north after midnight. Winds could gust as high as 26 mph. Chance of precipitation is 90%.

    Low: 43 °F

    Showers

  • Friday

    Friday: Rain, mainly before 7am. High near 52. Chance of precipitation is 80%.

    High: 52 °F

    Rain then
    Chance Rain

  • Friday Night

    Friday Night: Mostly clear, with a low around 32.

    Low: 32 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 58.

    High: 58 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 42.

    Low: 42 °F

    Partly Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a low around 43. Southeast wind around 6 mph.
Wednesday
Mostly sunny, with a high near 77. Southeast wind 5 to 11 mph becoming south in the afternoon.
Wednesday Night
A slight chance of showers and thunderstorms between 11pm and midnight. Mostly cloudy, then gradually becoming clear, with a low around 64. South wind around 10 mph. Chance of precipitation is 20%.
Thursday
A 20 percent chance of rain after 1pm. Sunny, with a high near 90. Southwest wind 9 to 14 mph, with gusts as high as 26 mph.
Thursday Night
Showers and possibly a thunderstorm before 4am, then rain after 4am. Low around 43. Southwest wind 9 to 17 mph becoming north after midnight. Winds could gust as high as 26 mph. Chance of precipitation is 90%.
Friday
Rain, mainly before 7am. High near 52. Chance of precipitation is 80%.
Friday Night
Mostly clear, with a low around 32.
Saturday
Sunny, with a high near 58.
Saturday Night
Partly cloudy, with a low around 42.
Sunday
Partly sunny, with a high near 64.
Sunday Night
Mostly cloudy, with a low around 53.
Monday
A 20 percent chance of rain and thunderstorms. Mostly sunny, with a high near 82.
Monday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 60.
Tuesday
A 40 percent chance of rain and thunderstorms. Partly sunny, with a high near 80.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.91°N 90.16°W (Elev. 505 ft)
Last Update:
1:26 am CDT Mar 25, 2026
Forecast Valid:
1am CDT Mar 25, 2026-6pm CDT Mar 31, 2026
 
Forecast Discussion
 
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Additional Resources

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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