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

42°F

6°C

Humidity 68%
Wind Speed Calm
Barometer 29.66 in (1004.5 mb)
Dewpoint 32°F (0°C)
Visibility 10.00 mi
Last update 18 Feb 8:54 pm CST
Extended Forecast for

Illiopolis IL

  • Tonight

    Tonight: A slight chance of showers and thunderstorms between midnight and 1am. Patchy fog after 3am. Otherwise, mostly cloudy, with a low around 45. Southeast wind 3 to 6 mph. Chance of precipitation is 20%.

    Low: 45 °F

    Mostly Cloudy
    then Slight
    Chance
    T-storms and
    Patchy Fog

  • Thursday

    Thursday: A chance of showers, mainly between 11am and noon, then a chance of rain and thunderstorms after noon. Areas of fog before 10am. Otherwise, mostly cloudy, with a high near 67. Southeast wind 7 to 15 mph becoming south southwest in the afternoon. Winds could gust as high as 22 mph. Chance of precipitation is 40%.

    High: 67 °F

    Chance
    Showers and
    Areas Fog
    then Chance
    T-storms

  • Thursday Night

    Thursday Night: A 30 percent chance of rain before midnight. Partly cloudy, with a low around 36. Breezy, with a southwest wind 10 to 15 mph increasing to 17 to 22 mph after midnight. Winds could gust as high as 31 mph.

    Low: 36 °F

    Chance Rain
    then Partly
    Cloudy and
    Breezy

  • Friday

    Friday: Mostly sunny, with a high near 46. Breezy, with a west wind 13 to 23 mph, with gusts as high as 32 mph.

    High: 46 °F

    Mostly Sunny
    and Breezy

  • Friday Night

    Friday Night: Mostly clear, with a low around 26. Northwest wind 7 to 10 mph, with gusts as high as 16 mph.

    Low: 26 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 41. West northwest wind 8 to 14 mph, with gusts as high as 20 mph.

    High: 41 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 22. Northwest wind 10 to 16 mph, with gusts as high as 23 mph.

    Low: 22 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 35. Breezy.

    High: 35 °F

    Partly Sunny
    and Breezy

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 18.

    Low: 18 °F

    Partly Cloudy

Detailed Forecast

Tonight
A slight chance of showers and thunderstorms between midnight and 1am. Patchy fog after 3am. Otherwise, mostly cloudy, with a low around 45. Southeast wind 3 to 6 mph. Chance of precipitation is 20%.
Thursday
A chance of showers, mainly between 11am and noon, then a chance of rain and thunderstorms after noon. Areas of fog before 10am. Otherwise, mostly cloudy, with a high near 67. Southeast wind 7 to 15 mph becoming south southwest in the afternoon. Winds could gust as high as 22 mph. Chance of precipitation is 40%.
Thursday Night
A 30 percent chance of rain before midnight. Partly cloudy, with a low around 36. Breezy, with a southwest wind 10 to 15 mph increasing to 17 to 22 mph after midnight. Winds could gust as high as 31 mph.
Friday
Mostly sunny, with a high near 46. Breezy, with a west wind 13 to 23 mph, with gusts as high as 32 mph.
Friday Night
Mostly clear, with a low around 26. Northwest wind 7 to 10 mph, with gusts as high as 16 mph.
Saturday
Sunny, with a high near 41. West northwest wind 8 to 14 mph, with gusts as high as 20 mph.
Saturday Night
Partly cloudy, with a low around 22. Northwest wind 10 to 16 mph, with gusts as high as 23 mph.
Sunday
Partly sunny, with a high near 35. Breezy.
Sunday Night
Partly cloudy, with a low around 18.
Monday
Sunny, with a high near 35.
Monday Night
Mostly clear, with a low around 19.
Tuesday
Partly sunny, with a high near 45.
Tuesday Night
Mostly cloudy, with a low around 35.
Wednesday
A chance of rain. Partly sunny, with a high near 52.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Illiopolis IL
 39.83°N 89.23°W (Elev. 568 ft)
Last Update:
9:36 pm CST Feb 18, 2026
Forecast Valid:
9pm CST Feb 18, 2026-6pm CST Feb 25, 2026
 
Forecast Discussion
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation