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

Hazardous Weather Conditions

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Mostly Cloudy

82°F

28°C

Humidity 62%
Wind Speed Vrbl 6 mph
Barometer 30.17 in
Dewpoint 68°F (20°C)
Visibility 10.00 mi
Heat Index85°F (29°C)
Last update 5 Aug 4:50 pm CDT
Extended Forecast for

Williamson IL

  • Tonight

    Tonight: A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers between 7pm and 8pm. Patchy fog after 5am. Otherwise, mostly clear, with a low around 66. Calm wind. Chance of precipitation is 20%.

    Low: 66 °F

    Slight Chance
    T-storms then
    Patchy Fog

  • Wednesday

    Wednesday: Patchy fog before 8am. Otherwise, mostly sunny, with a high near 86. Calm wind.

    High: 86 °F

    Patchy Fog
    then Mostly
    Sunny

  • Wednesday Night

    Wednesday Night: Increasing clouds, with a low around 68. Calm wind.

    Low: 68 °F

    Increasing
    Clouds

  • Thursday

    Thursday: Sunny, with a high near 88. Calm wind becoming south around 6 mph in the morning.

    High: 88 °F

    Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 69. South wind 3 to 5 mph.

    Low: 69 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 89.

    High: 89 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 70.

    Low: 70 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 89.

    High: 89 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 71.

    Low: 71 °F

    Mostly Clear

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms before 7pm, then a slight chance of showers between 7pm and 8pm. Patchy fog after 5am. Otherwise, mostly clear, with a low around 66. Calm wind. Chance of precipitation is 20%.
Wednesday
Patchy fog before 8am. Otherwise, mostly sunny, with a high near 86. Calm wind.
Wednesday Night
Increasing clouds, with a low around 68. Calm wind.
Thursday
Sunny, with a high near 88. Calm wind becoming south around 6 mph in the morning.
Thursday Night
Mostly clear, with a low around 69. South wind 3 to 5 mph.
Friday
Sunny, with a high near 89.
Friday Night
Mostly clear, with a low around 70.
Saturday
Sunny, with a high near 89.
Saturday Night
Mostly clear, with a low around 71.
Sunday
Sunny, with a high near 89.
Sunday Night
A 20 percent chance of showers and thunderstorms. Partly cloudy, with a low around 72.
Monday
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 89.
Monday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 72.
Tuesday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 89.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Williamson IL
 38.98°N 89.76°W (Elev. 597 ft)
Last Update:
5:41 pm CDT Aug 5, 2025
Forecast Valid:
6pm CDT Aug 5, 2025-6pm CDT Aug 12, 2025
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation