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

Heat Builds in the West; Extremely Critical Fire Weather in the Northwest

A heat wave over the Southwest will intensify this week, peaking and expanding into the Intermountain West and northern High Plains this weekend. Critical to extremely critical fire weather conditions are forecast from the Northwest and the northern Great Basin this weekend. Particularly Dangerous Situation Red Flag Warnings have been issued. Read More >

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Mostly Cloudy

73°F

23°C

Humidity 74%
Wind Speed N 14 mph
Barometer 29.87 in
Dewpoint 64°F (18°C)
Visibility 10.00 mi
Last update 2 Aug 10:50 am CDT
Extended Forecast for

Williamson IL

  • Today

    Today: Mostly sunny, with a high near 81. North wind around 14 mph, with gusts as high as 22 mph.

    High: 81 °F

    Mostly Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 62. North wind 5 to 9 mph becoming calm in the evening.

    Low: 62 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 83. Light northeast wind.

    High: 83 °F

    Sunny

  • Monday Night

    Monday Night: Clear, with a low around 62. Calm wind.

    Low: 62 °F

    Clear

  • Tuesday

    Tuesday: Sunny, with a high near 86. Light south wind.

    High: 86 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 63.

    Low: 63 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 87.

    High: 87 °F

    Sunny

  • Wednesday Night

    Wednesday Night: A 40 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 68.

    Low: 68 °F

    Partly Cloudy
    then Chance
    T-storms

  • Thursday

    Thursday: A 50 percent chance of showers and thunderstorms before 1pm. Partly sunny, with a high near 84.

    High: 84 °F

    Chance
    Showers

Detailed Forecast

Today
Mostly sunny, with a high near 81. North wind around 14 mph, with gusts as high as 22 mph.
Tonight
Mostly clear, with a low around 62. North wind 5 to 9 mph becoming calm in the evening.
Monday
Sunny, with a high near 83. Light northeast wind.
Monday Night
Clear, with a low around 62. Calm wind.
Tuesday
Sunny, with a high near 86. Light south wind.
Tuesday Night
Mostly clear, with a low around 63.
Wednesday
Sunny, with a high near 87.
Wednesday Night
A 40 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 68.
Thursday
A 50 percent chance of showers and thunderstorms before 1pm. Partly sunny, with a high near 84.
Thursday Night
A 40 percent chance of showers and thunderstorms, mainly after 1am. Partly cloudy, with a low around 68.
Friday
A 30 percent chance of showers and thunderstorms. Mostly sunny, with a high near 86.
Friday Night
A 30 percent chance of showers and thunderstorms. Partly cloudy, with a low around 68.
Saturday
A 20 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:
11:11 am CDT Aug 2, 2026
Forecast Valid:
11am CDT Aug 2, 2026-6pm CDT Aug 8, 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