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

NWS St. Louis Announces Changes To May 16, 2025 Tornado Damage Assessment

After a year-long review of new ground survey data and aerial imagery, NWS St. Louis made several adjustments to the May 16, 2025 tornado damage assessment. Read More >

Hazardous Weather Conditions

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

77°F

25°C

Humidity 62%
Wind Speed S 13 mph
Barometer 29.88 in
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Heat Index79°F (26°C)
Last update 17 May 11:15 pm CDT
Extended Forecast for

Alton IL

  • Overnight

    Overnight: Partly cloudy, with a low around 71. South wind around 11 mph, with gusts as high as 21 mph.

    Low: 71 °F

    Partly Cloudy

  • Monday

    Monday: Showers and thunderstorms likely, mainly between 11am and 2pm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 87. South wind 13 to 17 mph, with gusts as high as 26 mph. Chance of precipitation is 60%.

    High: 87 °F

    Heavy Rain

  • Monday Night

    Monday Night: Showers and thunderstorms likely, mainly after 4am. Partly cloudy, with a low around 69. South wind 13 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 60%.

    Low: 69 °F

    Slight Chance
    T-storms then
    T-storms
    Likely

  • Tuesday

    Tuesday: Showers and thunderstorms. High near 85. South wind 11 to 14 mph becoming west in the afternoon. Winds could gust as high as 23 mph. Chance of precipitation is 90%.

    High: 85 °F

    T-storms

  • Tuesday Night

    Tuesday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 56. Northwest wind 7 to 10 mph.

    Low: 56 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: Partly sunny, with a high near 70.

    High: 70 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 50.

    Low: 50 °F

    Mostly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 72.

    High: 72 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Mostly cloudy, with a low around 55.

    Low: 55 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Partly cloudy, with a low around 71. South wind around 11 mph, with gusts as high as 21 mph.
Monday
Showers and thunderstorms likely, mainly between 11am and 2pm. Some of the storms could produce heavy rainfall. Mostly cloudy, with a high near 87. South wind 13 to 17 mph, with gusts as high as 26 mph. Chance of precipitation is 60%.
Monday Night
Showers and thunderstorms likely, mainly after 4am. Partly cloudy, with a low around 69. South wind 13 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 60%.
Tuesday
Showers and thunderstorms. High near 85. South wind 11 to 14 mph becoming west in the afternoon. Winds could gust as high as 23 mph. Chance of precipitation is 90%.
Tuesday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 56. Northwest wind 7 to 10 mph.
Wednesday
Partly sunny, with a high near 70.
Wednesday Night
Mostly cloudy, with a low around 50.
Thursday
Mostly sunny, with a high near 72.
Thursday Night
Mostly cloudy, with a low around 55.
Friday
A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 76.
Friday Night
A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 59.
Saturday
A 30 percent chance of showers and thunderstorms. Partly sunny, with a high near 82.
Saturday Night
A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 62.
Sunday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 87.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Alton IL
 38.88°N 90.16°W (Elev. 466 ft)
Last Update:
1:16 am CDT May 18, 2026
Forecast Valid:
1am CDT May 18, 2026-6pm CDT May 24, 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