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Current conditions at

Decatur Airport (KDEC)

Lat: 39.83°NLon: 88.87°WElev: 670ft.

Fair

77°F

25°C

Humidity 54%
Wind Speed SW 8 mph
Barometer 29.85 in (1010.4 mb)
Dewpoint 59°F (15°C)
Visibility 8.00 mi
Heat Index79°F (26°C)
Last update 12 Oct 7:54 pm CDT
Extended Forecast for

Harristown IL

  • Tonight

    Tonight: Mostly clear, with a low around 70. Southwest wind 10 to 13 mph, with gusts as high as 18 mph.

    Low: 70 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 91. Southwest wind 10 to 13 mph, with gusts as high as 18 mph.

    High: 91 °F

    Sunny

  • Tuesday Night

    Tuesday Night: A 50 percent chance of showers and thunderstorms, mainly after 1am. Increasing clouds, with a low around 69. Southwest wind 5 to 7 mph.

    Low: 69 °F

    Mostly Clear
    then Chance
    T-storms

  • Wednesday

    Wednesday: Showers. High near 79. Light and variable wind becoming west around 6 mph in the morning. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

    High: 79 °F

    Showers

  • Wednesday Night

    Wednesday Night: A 40 percent chance of showers. Mostly cloudy, with a low around 60. Northeast wind 7 to 10 mph.

    Low: 60 °F

    Chance
    Showers

  • Thursday

    Thursday: Showers, with thunderstorms also possible after 1pm. High near 75. East northeast wind around 9 mph becoming south southwest in the afternoon. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

    High: 75 °F

    Showers

  • Thursday Night

    Thursday Night: A 30 percent chance of showers before 1am. Mostly cloudy, with a low around 50. Breezy, with a west northwest wind 9 to 14 mph increasing to 17 to 22 mph after midnight. Winds could gust as high as 28 mph.

    Low: 50 °F

    Chance
    Showers and
    Breezy

  • Friday

    Friday: Mostly sunny, with a high near 61. Breezy.

    High: 61 °F

    Mostly Sunny
    and Breezy

  • Friday Night

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

    Low: 37 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly clear, with a low around 70. Southwest wind 10 to 13 mph, with gusts as high as 18 mph.
Tuesday
Sunny, with a high near 91. Southwest wind 10 to 13 mph, with gusts as high as 18 mph.
Tuesday Night
A 50 percent chance of showers and thunderstorms, mainly after 1am. Increasing clouds, with a low around 69. Southwest wind 5 to 7 mph.
Wednesday
Showers. High near 79. Light and variable wind becoming west around 6 mph in the morning. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.
Wednesday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 60. Northeast wind 7 to 10 mph.
Thursday
Showers, with thunderstorms also possible after 1pm. High near 75. East northeast wind around 9 mph becoming south southwest in the afternoon. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Thursday Night
A 30 percent chance of showers before 1am. Mostly cloudy, with a low around 50. Breezy, with a west northwest wind 9 to 14 mph increasing to 17 to 22 mph after midnight. Winds could gust as high as 28 mph.
Friday
Mostly sunny, with a high near 61. Breezy.
Friday Night
Mostly clear, with a low around 37.
Saturday
Sunny, with a high near 61.
Saturday Night
Mostly clear, with a low around 38.
Sunday
Sunny, with a high near 68.
Sunday Night
Partly cloudy, with a low around 46.
Monday
Mostly sunny, with a high near 73.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Harristown IL
 39.84°N 89.06°W (Elev. 699 ft)
Last Update:
7:36 pm CDT Oct 12, 2026
Forecast Valid:
8pm CDT Oct 12, 2026-6pm CDT Oct 19, 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