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.

Fog/Mist

49°F

9°C

Humidity 100%
Wind Speed W 6 mph
Barometer 30.00 in (1016.1 mb)
Dewpoint 49°F (9°C)
Visibility 0.75 mi
Wind Chill46°F (8°C)
Last update 5 Mar 8:54 am CST
Extended Forecast for

Illiopolis IL

  • Today

    Today: A 30 percent chance of showers before 11am. Areas of fog before noon. Otherwise, cloudy, with a high near 60. West wind 5 to 8 mph.

    High: 60 °F

    Chance
    Showers and
    Areas Fog
    then Cloudy

  • Tonight

    Tonight: A 50 percent chance of showers and thunderstorms after 3am. Widespread fog, mainly before 3am. Otherwise, mostly cloudy, with a low around 50. Light and variable wind becoming south southeast 5 to 10 mph in the evening. Winds could gust as high as 17 mph.

    Low: 50 °F

    Fog then
    Chance
    T-storms and
    Fog

  • Friday

    Friday: A chance of showers and thunderstorms before noon, then a slight chance of showers. Patchy fog before 9am. Otherwise, partly sunny, with a high near 76. Breezy, with a south wind 11 to 16 mph increasing to 18 to 23 mph in the afternoon. Winds could gust as high as 33 mph. Chance of precipitation is 40%.

    High: 76 °F

    Chance
    T-storms and
    Patchy Fog

  • Friday Night

    Friday Night: A chance of showers, then showers and possibly a thunderstorm after midnight. Low around 58. Breezy, with a south wind 16 to 21 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

    Low: 58 °F

    Breezy.
    Chance
    Showers then
    Showers

  • Saturday

    Saturday: A 50 percent chance of showers before noon. Mostly cloudy, with a temperature rising to near 62 by 9am, then falling to around 53 during the remainder of the day. Southwest wind 13 to 18 mph becoming west northwest in the afternoon. Winds could gust as high as 28 mph.

    High: 62 °F⇓

    Chance
    Showers then
    Partly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 37. West northwest wind 6 to 11 mph, with gusts as high as 17 mph.

    Low: 37 °F

    Partly Cloudy

  • Sunday

    Sunday: Sunny, with a high near 62. Southwest wind 6 to 14 mph, with gusts as high as 20 mph.

    High: 62 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 45.

    Low: 45 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 74.

    High: 74 °F

    Sunny

Detailed Forecast

Today
A 30 percent chance of showers before 11am. Areas of fog before noon. Otherwise, cloudy, with a high near 60. West wind 5 to 8 mph.
Tonight
A 50 percent chance of showers and thunderstorms after 3am. Widespread fog, mainly before 3am. Otherwise, mostly cloudy, with a low around 50. Light and variable wind becoming south southeast 5 to 10 mph in the evening. Winds could gust as high as 17 mph.
Friday
A chance of showers and thunderstorms before noon, then a slight chance of showers. Patchy fog before 9am. Otherwise, partly sunny, with a high near 76. Breezy, with a south wind 11 to 16 mph increasing to 18 to 23 mph in the afternoon. Winds could gust as high as 33 mph. Chance of precipitation is 40%.
Friday Night
A chance of showers, then showers and possibly a thunderstorm after midnight. Low around 58. Breezy, with a south wind 16 to 21 mph, with gusts as high as 30 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Saturday
A 50 percent chance of showers before noon. Mostly cloudy, with a temperature rising to near 62 by 9am, then falling to around 53 during the remainder of the day. Southwest wind 13 to 18 mph becoming west northwest in the afternoon. Winds could gust as high as 28 mph.
Saturday Night
Partly cloudy, with a low around 37. West northwest wind 6 to 11 mph, with gusts as high as 17 mph.
Sunday
Sunny, with a high near 62. Southwest wind 6 to 14 mph, with gusts as high as 20 mph.
Sunday Night
Mostly clear, with a low around 45.
Monday
Sunny, with a high near 74.
Monday Night
A 40 percent chance of showers and thunderstorms after midnight. Partly cloudy, with a low around 57.
Tuesday
Showers and possibly a thunderstorm. Mostly cloudy, with a high near 73. Breezy.
Tuesday Night
Showers. Cloudy, with a low around 48. Breezy.
Wednesday
Showers likely. Mostly cloudy, with a high near 58. Breezy.
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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:
8:26 am CST Mar 5, 2026
Forecast Valid:
9am CST Mar 5, 2026-6pm CDT Mar 11, 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