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

Decatur Airport (KDEC)

Lat: 39.83°NLon: 88.87°WElev: 670ft.

Fair

53°F

12°C

Humidity 59%
Wind Speed Calm
Barometer 29.84 in (1010.4 mb)
Dewpoint 39°F (4°C)
Visibility 10.00 mi
Last update 8 Nov 12:54 pm CST
Extended Forecast for

Illiopolis IL

  • This Afternoon

    This Afternoon: A 30 percent chance of rain, mainly after 3pm. Mostly cloudy, with a high near 55. Northwest wind around 6 mph becoming east.

    High: 55 °F

    Chance Rain

  • Tonight

    Tonight: Rain before 3am, then a slight chance of rain and snow between 3am and 5am, then a slight chance of snow after 5am. Low around 32. Breezy, with an east wind 7 to 12 mph becoming north northwest 16 to 21 mph in the evening. Winds could gust as high as 33 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.

    Low: 32 °F

    Rain then
    Chance
    Rain/Snow and
    Breezy

  • Sunday

    Sunday: A 10 percent chance of snow showers. Partly sunny, with a high near 38. Breezy, with a north northwest wind 18 to 22 mph, with gusts as high as 31 mph.

    High: 38 °F

    Slight Chance
    Snow Showers
    and Breezy

  • Sunday Night

    Sunday Night: A chance of flurries before midnight. Partly cloudy, with a low around 23. Northwest wind 14 to 17 mph, with gusts as high as 25 mph.

    Low: 23 °F

    Chance
    Flurries

  • Monday

    Monday: Sunny, with a high near 38. Breezy, with a northwest wind 13 to 20 mph, with gusts as high as 25 mph.

    High: 38 °F

    Sunny then
    Sunny and
    Breezy

  • Monday Night

    Monday Night: Partly cloudy, with a low around 23. West northwest wind 6 to 10 mph becoming south southwest after midnight. Winds could gust as high as 16 mph.

    Low: 23 °F

    Partly Cloudy

  • Veterans Day

    Veterans Day: Partly sunny, with a high near 51. Breezy, with a south southwest wind 11 to 20 mph, with gusts as high as 28 mph.

    High: 51 °F

    Partly Sunny
    and Breezy

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 37.

    Low: 37 °F

    Mostly Clear

  • Wednesday

    Wednesday: Sunny, with a high near 59.

    High: 59 °F

    Sunny

Detailed Forecast

This Afternoon
A 30 percent chance of rain, mainly after 3pm. Mostly cloudy, with a high near 55. Northwest wind around 6 mph becoming east.
Tonight
Rain before 3am, then a slight chance of rain and snow between 3am and 5am, then a slight chance of snow after 5am. Low around 32. Breezy, with an east wind 7 to 12 mph becoming north northwest 16 to 21 mph in the evening. Winds could gust as high as 33 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.
Sunday
A 10 percent chance of snow showers. Partly sunny, with a high near 38. Breezy, with a north northwest wind 18 to 22 mph, with gusts as high as 31 mph.
Sunday Night
A chance of flurries before midnight. Partly cloudy, with a low around 23. Northwest wind 14 to 17 mph, with gusts as high as 25 mph.
Monday
Sunny, with a high near 38. Breezy, with a northwest wind 13 to 20 mph, with gusts as high as 25 mph.
Monday Night
Partly cloudy, with a low around 23. West northwest wind 6 to 10 mph becoming south southwest after midnight. Winds could gust as high as 16 mph.
Veterans Day
Partly sunny, with a high near 51. Breezy, with a south southwest wind 11 to 20 mph, with gusts as high as 28 mph.
Tuesday Night
Mostly clear, with a low around 37.
Wednesday
Sunny, with a high near 59.
Wednesday Night
Mostly clear, with a low around 33.
Thursday
Sunny, with a high near 58.
Thursday Night
Partly cloudy, with a low around 38.
Friday
Mostly sunny, with a high near 63.
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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:
12:36 pm CST Nov 8, 2025
Forecast Valid:
1pm CST Nov 8, 2025-6pm CST Nov 14, 2025
 
Forecast Discussion
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation