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

Heavy Rainfall and Severe Thunderstorm Threats; Heat Risk Expands; Monitoring the Tropics

Flash flooding risks continue for portions of the Four Corners and Great Basin through today. Severe thunderstorms are outlooked from the eastern Great Lakes, southern New England into the mid-Atlantic through Tuesday. Heat risk increases and expands across the center of the nation and across the Ohio Valley and mid-Atlantic this week. Continue to closely monitor tropical development in the Gulf. Read More >

Hazardous Weather Conditions

Current conditions at

St. Louis Regional Airport (KALN)

Lat: 38.89°NLon: 90.03°WElev: 518ft.

Fair

70°F

21°C

Humidity 78%
Wind Speed S 8 mph
Barometer 30.02 in
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Last update 31 Aug 6:50 am CDT
Extended Forecast for

Dorchester IL

Heat Advisory August 31, 12:00pm until September 4, 08:00pm
Click here for hazard details and duration
Heat Advisory

  • Today

    Today: Sunny, with a high near 96. Heat index values as high as 100. Southwest wind 7 to 10 mph.

    High: 96 °F

    Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 74. South wind around 7 mph.

    Low: 74 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny and hot, with a high near 98. Heat index values as high as 103. Southwest wind 5 to 7 mph.

    High: 98 °F

    Hot

  • Tuesday Night

    Tuesday Night: Clear, with a low around 76. South wind 3 to 6 mph.

    Low: 76 °F

    Clear

  • Wednesday

    Wednesday: Sunny and hot, with a high near 98. Southwest wind 5 to 8 mph.

    High: 98 °F

    Hot

  • Wednesday Night

    Wednesday Night: Clear, with a low around 77.

    Low: 77 °F

    Clear

  • Thursday

    Thursday: Sunny and hot, with a high near 98.

    High: 98 °F

    Hot

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 75.

    Low: 75 °F

    Mostly Clear

  • Friday

    Friday: A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 92.

    High: 92 °F

    Sunny then
    Slight Chance
    T-storms

Detailed Forecast

Today
Sunny, with a high near 96. Heat index values as high as 100. Southwest wind 7 to 10 mph.
Tonight
Mostly clear, with a low around 74. South wind around 7 mph.
Tuesday
Sunny and hot, with a high near 98. Heat index values as high as 103. Southwest wind 5 to 7 mph.
Tuesday Night
Clear, with a low around 76. South wind 3 to 6 mph.
Wednesday
Sunny and hot, with a high near 98. Southwest wind 5 to 8 mph.
Wednesday Night
Clear, with a low around 77.
Thursday
Sunny and hot, with a high near 98.
Thursday Night
Mostly clear, with a low around 75.
Friday
A 20 percent chance of showers and thunderstorms after 1pm. Sunny, with a high near 92.
Friday Night
A 20 percent chance of showers and thunderstorms after 1am. Mostly clear, with a low around 72.
Saturday
A 20 percent chance of showers and thunderstorms. Sunny, with a high near 91.
Saturday Night
Mostly clear, with a low around 70.
Sunday
Sunny, with a high near 89.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Dorchester IL
 39.08°N 89.9°W (Elev. 659 ft)
Last Update:
5:21 am CDT Aug 31, 2026
Forecast Valid:
7am CDT Aug 31, 2026-6pm CDT Sep 6, 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