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.

Thunderstorm in Vicinity

74°F

23°C

Humidity 88%
Wind Speed SE 9 mph
Barometer 30.11 in (1018.9 mb)
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Last update 17 Aug 9:54 am CDT
Extended Forecast for

2 Miles S Illiopolis IL

Heat Advisory August 17, 10:01am until August 17, 08:00pm
Click here for hazard details and duration
Heat Advisory
  •  
    Heat Advisory August 17, 10:01am until August 17, 08:00pm

    NOW until 8:00pm Sun

    Heat Advisory

  • Today

    High: 92 °F

    Slight Chance
    T-storms

  • Tonight

    Tonight: Partly cloudy, with a low around 74. Calm wind becoming east around 5 mph after midnight.

    Low: 74 °F

    Partly Cloudy

  • Monday

    Monday: A 20 percent chance of showers and thunderstorms before 1pm. Sunny, with a high near 92. Heat index values as high as 105. East southeast wind around 6 mph.

    High: 92 °F

    Slight Chance
    T-storms

  • Monday Night

    Monday Night: Mostly clear, with a low around 73. Southeast wind around 5 mph.

    Low: 73 °F

    Mostly Clear

  • Tuesday

    Tuesday: A chance of showers, with thunderstorms also possible after 10am. Mostly sunny, with a high near 91. South wind around 6 mph becoming west northwest in the afternoon. Chance of precipitation is 30%.

    High: 91 °F

    Chance
    T-storms

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 70. North wind around 6 mph.

    Low: 70 °F

    Chance
    T-storms

  • Wednesday

    Wednesday: Partly sunny, with a high near 82. North northeast wind 6 to 10 mph, with gusts as high as 15 mph.

    High: 82 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 66.

    Low: 66 °F

    Partly Cloudy

Detailed Forecast

Today
A slight chance of showers and thunderstorms before 11am, then a slight chance of showers and thunderstorms after 2pm. Mostly sunny, with a high near 92. Heat index values as high as 101. Light and variable wind. Chance of precipitation is 20%.
Tonight
Partly cloudy, with a low around 74. Calm wind becoming east around 5 mph after midnight.
Monday
A 20 percent chance of showers and thunderstorms before 1pm. Sunny, with a high near 92. Heat index values as high as 105. East southeast wind around 6 mph.
Monday Night
Mostly clear, with a low around 73. Southeast wind around 5 mph.
Tuesday
A chance of showers, with thunderstorms also possible after 10am. Mostly sunny, with a high near 91. South wind around 6 mph becoming west northwest in the afternoon. Chance of precipitation is 30%.
Tuesday Night
A 30 percent chance of showers and thunderstorms before 1am. Mostly cloudy, with a low around 70. North wind around 6 mph.
Wednesday
Partly sunny, with a high near 82. North northeast wind 6 to 10 mph, with gusts as high as 15 mph.
Wednesday Night
Partly cloudy, with a low around 66.
Thursday
Mostly sunny, with a high near 83.
Thursday Night
Mostly clear, with a low around 65.
Friday
Sunny, with a high near 86.
Friday Night
Mostly clear, with a low around 64.
Saturday
Sunny, with a high near 86.
Basemap Options
Click map to change the forecast location
Loading map...
Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
2 Miles S Illiopolis IL
 39.83°N 89.26°W (Elev. 600 ft)
Last Update:
9:12 am CDT Aug 17, 2025
Forecast Valid:
10am CDT Aug 17, 2025-6pm CDT Aug 23, 2025
 
Forecast Discussion
 
Get as KML Get as XML

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