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

67°F

19°C

Humidity 44%
Wind Speed NW 17 G 24 mph
Barometer 30.05 in (1017.5 mb)
Dewpoint 44°F (7°C)
Visibility 10.00 mi
Last update 5 Nov 12:54 pm CST
Extended Forecast for

Illiopolis IL

  • This Afternoon

    This Afternoon: Sunny, with a high near 67. Breezy, with a north northwest wind 13 to 20 mph, with gusts as high as 30 mph.

    High: 67 °F

    Sunny and
    Breezy

  • Tonight

    Tonight: Mostly clear, with a low around 33. North northwest wind 5 to 9 mph becoming light and variable after midnight. Winds could gust as high as 16 mph.

    Low: 33 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 62. Light east wind becoming south southeast 11 to 16 mph in the morning. Winds could gust as high as 22 mph.

    High: 62 °F

    Sunny

  • Thursday Night

    Thursday Night: A 50 percent chance of rain after midnight. Mostly cloudy, with a low around 50. South southeast wind 14 to 16 mph becoming southwest after midnight. Winds could gust as high as 23 mph.

    Low: 50 °F

    Mostly Cloudy
    then Chance
    Rain

  • Friday

    Friday: A 30 percent chance of rain before noon. Mostly cloudy, then gradually becoming sunny, with a high near 70. West wind 13 to 17 mph, with gusts as high as 23 mph.

    High: 70 °F

    Chance Rain
    then Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 39. West northwest wind 5 to 10 mph, with gusts as high as 15 mph.

    Low: 39 °F

    Mostly Clear

  • Saturday

    Saturday: A 30 percent chance of rain after noon. Partly sunny, with a high near 60. North northwest wind 5 to 11 mph becoming south southwest in the afternoon. Winds could gust as high as 17 mph.

    High: 60 °F

    Mostly Sunny
    then Chance
    Rain

  • Saturday Night

    Saturday Night: A 40 percent chance of rain before midnight. Mostly cloudy, with a low around 32.

    Low: 32 °F

    Chance Rain
    then Mostly
    Cloudy

  • Sunday

    Sunday: Mostly sunny, with a high near 41. Breezy.

    High: 41 °F

    Mostly Sunny
    and Breezy

Detailed Forecast

This Afternoon
Sunny, with a high near 67. Breezy, with a north northwest wind 13 to 20 mph, with gusts as high as 30 mph.
Tonight
Mostly clear, with a low around 33. North northwest wind 5 to 9 mph becoming light and variable after midnight. Winds could gust as high as 16 mph.
Thursday
Sunny, with a high near 62. Light east wind becoming south southeast 11 to 16 mph in the morning. Winds could gust as high as 22 mph.
Thursday Night
A 50 percent chance of rain after midnight. Mostly cloudy, with a low around 50. South southeast wind 14 to 16 mph becoming southwest after midnight. Winds could gust as high as 23 mph.
Friday
A 30 percent chance of rain before noon. Mostly cloudy, then gradually becoming sunny, with a high near 70. West wind 13 to 17 mph, with gusts as high as 23 mph.
Friday Night
Mostly clear, with a low around 39. West northwest wind 5 to 10 mph, with gusts as high as 15 mph.
Saturday
A 30 percent chance of rain after noon. Partly sunny, with a high near 60. North northwest wind 5 to 11 mph becoming south southwest in the afternoon. Winds could gust as high as 17 mph.
Saturday Night
A 40 percent chance of rain before midnight. Mostly cloudy, with a low around 32.
Sunday
Mostly sunny, with a high near 41. Breezy.
Sunday Night
Mostly clear, with a low around 21.
Monday
Sunny, with a high near 41.
Monday Night
Mostly clear, with a low around 23.
Veterans Day
Mostly sunny, with a high near 50.
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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:
12:36 pm CST Nov 5, 2025
Forecast Valid:
1pm CST Nov 5, 2025-6pm CST Nov 11, 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