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 and Breezy

12°F

-11°C

Humidity 58%
Wind Speed NW 23 G 36 mph
Barometer 30.08 in (1019.6 mb)
Dewpoint 0°F (-18°C)
Visibility 10.00 mi
Wind Chill-7°F (-22°C)
Last update 19 Jan 2:54 am CST
Extended Forecast for

Illiopolis IL

Cold Weather Advisory until January 19, 12:00pm
Click here for hazard details and duration
Cold Weather Advisory
  •  
    Cold Weather Advisory until January 19, 12:00pm

    NOW until 12:00pm Mon

    Cold Weather Advisory

  • Overnight

    Low: 5 °F

    Mostly Cloudy
    and Blustery

  • M.L.King Day

    M.L.King Day: Sunny, with a high near 14. Wind chill values between -6 and -16. Blustery, with a west northwest wind 11 to 21 mph, with gusts as high as 36 mph.

    High: 14 °F

    Sunny and
    Blustery

  • Monday Night

    Monday Night: Partly cloudy, with a low around 8. Wind chill values between -3 and 2. Southwest wind 5 to 9 mph, with gusts as high as 15 mph.

    Low: 8 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 31. Wind chill values between -2 and 8. South southwest wind 6 to 10 mph, with gusts as high as 15 mph.

    High: 31 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 25. South wind 9 to 18 mph, with gusts as high as 28 mph.

    Low: 25 °F

    Mostly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 38. West wind 10 to 17 mph, with gusts as high as 28 mph.

    High: 38 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 19. West northwest wind 9 to 14 mph, with gusts as high as 21 mph.

    Low: 19 °F

    Partly Cloudy

  • Thursday

    Thursday: Mostly sunny, with a high near 30.

    High: 30 °F

    Mostly Sunny

Detailed Forecast

Overnight
Mostly cloudy, with a low around 5. Wind chill values between -5 and -10. Blustery, with a west northwest wind around 22 mph, with gusts as high as 40 mph.
M.L.King Day
Sunny, with a high near 14. Wind chill values between -6 and -16. Blustery, with a west northwest wind 11 to 21 mph, with gusts as high as 36 mph.
Monday Night
Partly cloudy, with a low around 8. Wind chill values between -3 and 2. Southwest wind 5 to 9 mph, with gusts as high as 15 mph.
Tuesday
Mostly sunny, with a high near 31. Wind chill values between -2 and 8. South southwest wind 6 to 10 mph, with gusts as high as 15 mph.
Tuesday Night
Mostly cloudy, with a low around 25. South wind 9 to 18 mph, with gusts as high as 28 mph.
Wednesday
Mostly sunny, with a high near 38. West wind 10 to 17 mph, with gusts as high as 28 mph.
Wednesday Night
Partly cloudy, with a low around 19. West northwest wind 9 to 14 mph, with gusts as high as 21 mph.
Thursday
Mostly sunny, with a high near 30.
Thursday Night
Mostly cloudy, with a low around 11.
Friday
Mostly cloudy, with a high near 18.
Friday Night
Mostly cloudy, with a low around -3.
Saturday
Partly sunny, with a high near 11.
Saturday Night
A chance of snow. Mostly cloudy, with a low around 3.
Sunday
Mostly sunny, with a high near 20.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Illiopolis IL
 39.85°N 89.26°W (Elev. 607 ft)
Last Update:
3:36 am CST Jan 19, 2026
Forecast Valid:
3am CST Jan 19, 2026-6pm CST Jan 25, 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