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.

Light Rain Fog/Mist

65°F

18°C

Humidity 93%
Wind Speed E 5 mph
Barometer 29.97 in (1014.6 mb)
Dewpoint 63°F (17°C)
Visibility 5.00 mi
Last update 27 May 5:54 am CDT
Extended Forecast for

Illiopolis IL

  • Overnight

    Overnight: A 30 percent chance of showers and thunderstorms. Cloudy, with a low around 63. Calm wind.

    Low: 63 °F

    Chance
    Showers

  • Wednesday

    Wednesday: A 30 percent chance of showers and thunderstorms, mainly before 8am. Cloudy, then gradually becoming mostly sunny, with a high near 83. North northeast wind 3 to 7 mph.

    High: 83 °F

    Chance
    Showers then
    Partly Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 60. Northeast wind around 6 mph becoming calm.

    Low: 60 °F

    Mostly Clear

  • Thursday

    Thursday: Mostly sunny, with a high near 84. East northeast wind 8 to 11 mph, with gusts as high as 18 mph.

    High: 84 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 58. East wind around 9 mph, with gusts as high as 15 mph.

    Low: 58 °F

    Partly Cloudy

  • Friday

    Friday: Partly sunny, with a high near 80. East wind around 8 mph.

    High: 80 °F

    Partly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 59. East wind 3 to 6 mph.

    Low: 59 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 83.

    High: 83 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 58.

    Low: 58 °F

    Partly Cloudy

Detailed Forecast

Overnight
A 30 percent chance of showers and thunderstorms. Cloudy, with a low around 63. Calm wind.
Wednesday
A 30 percent chance of showers and thunderstorms, mainly before 8am. Cloudy, then gradually becoming mostly sunny, with a high near 83. North northeast wind 3 to 7 mph.
Wednesday Night
Mostly clear, with a low around 60. Northeast wind around 6 mph becoming calm.
Thursday
Mostly sunny, with a high near 84. East northeast wind 8 to 11 mph, with gusts as high as 18 mph.
Thursday Night
Partly cloudy, with a low around 58. East wind around 9 mph, with gusts as high as 15 mph.
Friday
Partly sunny, with a high near 80. East wind around 8 mph.
Friday Night
Partly cloudy, with a low around 59. East wind 3 to 6 mph.
Saturday
Mostly sunny, with a high near 83.
Saturday Night
Partly cloudy, with a low around 58.
Sunday
Mostly sunny, with a high near 78.
Sunday Night
Mostly clear, with a low around 56.
Monday
Sunny, with a high near 80.
Monday Night
Mostly clear, with a low around 56.
Tuesday
Sunny, with a high near 80.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Illiopolis IL
 39.85°N 89.26°W (Elev. 607 ft)
Last Update:
5:36 am CDT May 27, 2026
Forecast Valid:
5am CDT May 27, 2026-6pm CDT Jun 2, 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