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

Hazardous Weather Conditions

Current conditions at

Decatur Airport (KDEC)

Lat: 39.83°NLon: 88.87°WElev: 670ft.

Fair

89°F

32°C

Humidity 70%
Wind Speed SW 3 mph
Barometer 30.02 in (1015.7 mb)
Dewpoint 78°F (26°C)
Visibility 10.00 mi
Heat Index103°F (39°C)
Last update 17 Aug 5:54 pm CDT
Extended Forecast for

4 Miles WSW Sullivan IL

Heat Advisory August 17, 06:56pm until August 17, 08:00pm
Click here for hazard details and duration
...
  •  
    Heat Advisory August 17, 06:56pm until August 17, 08:00pm

    NOW until 8:00pm Sun

    Heat Advisory

  • Tonight

    Low: 71 °F

    Slight Chance
    T-storms then
    Mostly Cloudy

  • Monday

    Monday: A slight chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 91. Heat index values as high as 102. South wind around 6 mph. Chance of precipitation is 20%.

    High: 91 °F

    Slight Chance
    Showers then
    Slight Chance
    T-storms

  • Monday Night

    Monday Night: A 20 percent chance of showers and thunderstorms after 1am. Mostly clear, with a low around 72. Calm wind.

    Low: 72 °F

    Partly Cloudy
    then Slight
    Chance
    T-storms

  • Tuesday

    Tuesday: A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 89. Light and variable wind becoming south southwest around 5 mph in the morning.

    High: 89 °F

    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A chance of showers before 10pm, then a chance of showers and thunderstorms between 10pm and 1am. Mostly cloudy, with a low around 70. Calm wind. Chance of precipitation is 30%.

    Low: 70 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: Mostly sunny, with a high near 85. North northeast wind 5 to 8 mph.

    High: 85 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 64. North northeast wind 5 to 7 mph.

    Low: 64 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 84.

    High: 84 °F

    Mostly Sunny

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms between 7pm and 10pm. Mostly cloudy, with a low around 71. Light and variable wind becoming south southwest around 6 mph. Chance of precipitation is 20%.
Monday
A slight chance of showers, with thunderstorms also possible after 1pm. Partly sunny, with a high near 91. Heat index values as high as 102. South wind around 6 mph. Chance of precipitation is 20%.
Monday Night
A 20 percent chance of showers and thunderstorms after 1am. Mostly clear, with a low around 72. Calm wind.
Tuesday
A 40 percent chance of showers and thunderstorms. Mostly sunny, with a high near 89. Light and variable wind becoming south southwest around 5 mph in the morning.
Tuesday Night
A chance of showers before 10pm, then a chance of showers and thunderstorms between 10pm and 1am. Mostly cloudy, with a low around 70. Calm wind. Chance of precipitation is 30%.
Wednesday
Mostly sunny, with a high near 85. North northeast wind 5 to 8 mph.
Wednesday Night
Partly cloudy, with a low around 64. North northeast wind 5 to 7 mph.
Thursday
Mostly sunny, with a high near 84.
Thursday Night
Mostly clear, with a low around 63.
Friday
Sunny, with a high near 86.
Friday Night
Mostly clear, with a low around 64.
Saturday
Sunny, with a high near 85.
Saturday Night
Mostly clear, with a low around 58.
Sunday
Sunny, with a high near 79.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
4 Miles WSW Sullivan IL
 39.57°N 88.67°W (Elev. 676 ft)
Last Update:
6:40 pm CDT Aug 17, 2025
Forecast Valid:
6pm CDT Aug 17, 2025-6pm CDT Aug 24, 2025
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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