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

Dangerous Heat and Heavy Rainfall into the Weekend

Hot temperatures and high humidity are forecast to continue across the mid-Mississippi Valley into this weekend. Heat Advisories remain in effect. Heavy to excessive rainfall occurring at times through the weekend could bring areas of flooding to parts of the northern Rockies, upper Midwest, central Great Lakes, and southern New England. Read More >

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

88°F

31°C

Humidity 55%
Wind Speed NE 3 mph
Barometer 29.91 in
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Heat Index93°F (34°C)
Last update 20 Sep 12:50 pm CDT
Extended Forecast for

Pontoon Beach IL

  • This Afternoon

    This Afternoon: Partly sunny, with a high near 91. West wind around 7 mph.

    High: 91 °F

    Partly Sunny

  • Tonight

    Tonight: A chance of showers and thunderstorms before 1am, then showers likely and possibly a thunderstorm between 1am and 3am, then a chance of showers and thunderstorms after 3am. Mostly cloudy, with a low around 68. North wind 5 to 8 mph. Chance of precipitation is 60%.

    Low: 68 °F

    Chance
    T-storms then
    Showers
    Likely

  • Monday

    Monday: A 30 percent chance of showers, mainly before 9am. Mostly cloudy, with a high near 77. North wind 5 to 8 mph.

    High: 77 °F

    Chance
    Showers then
    Mostly Cloudy

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 62. Northeast wind 5 to 9 mph.

    Low: 62 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: Partly sunny, with a high near 74. Northeast wind 8 to 11 mph.

    High: 74 °F

    Partly Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 55.

    Low: 55 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 75.

    High: 75 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 55.

    Low: 55 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 77.

    High: 77 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
Partly sunny, with a high near 91. West wind around 7 mph.
Tonight
A chance of showers and thunderstorms before 1am, then showers likely and possibly a thunderstorm between 1am and 3am, then a chance of showers and thunderstorms after 3am. Mostly cloudy, with a low around 68. North wind 5 to 8 mph. Chance of precipitation is 60%.
Monday
A 30 percent chance of showers, mainly before 9am. Mostly cloudy, with a high near 77. North wind 5 to 8 mph.
Monday Night
Mostly cloudy, with a low around 62. Northeast wind 5 to 9 mph.
Tuesday
Partly sunny, with a high near 74. Northeast wind 8 to 11 mph.
Tuesday Night
Partly cloudy, with a low around 55.
Wednesday
Mostly sunny, with a high near 75.
Wednesday Night
Partly cloudy, with a low around 55.
Thursday
Mostly sunny, with a high near 77.
Thursday Night
Partly cloudy, with a low around 57.
Friday
Mostly sunny, with a high near 78.
Friday Night
Partly cloudy, with a low around 57.
Saturday
Partly sunny, with a high near 80.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Pontoon Beach IL
 38.73°N 90.06°W (Elev. 423 ft)
Last Update:
10:26 am CDT Sep 20, 2026
Forecast Valid:
1pm CDT Sep 20, 2026-6pm CDT Sep 26, 2026
 
Forecast Discussion
 
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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