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

65°F

18°C

Humidity 63%
Wind Speed S 7 mph
Barometer 29.93 in (1012.8 mb)
Dewpoint 52°F (11°C)
Visibility 10.00 mi
Last update 30 Sep 3:54 am CDT
Extended Forecast for

Harristown IL

  • Overnight

    Overnight: A 20 percent chance of showers before 5am. Cloudy, with a low around 62. South wind around 8 mph, with gusts as high as 15 mph.

    Low: 62 °F

    Slight Chance
    Showers

  • Wednesday

    Wednesday: A slight chance of showers between 7am and 11am. Mostly cloudy, with a high near 83. South wind around 9 mph, with gusts as high as 15 mph. Chance of precipitation is 20%.

    High: 83 °F

    Slight Chance
    Showers then
    Mostly Cloudy

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 69. South wind 7 to 11 mph, with gusts as high as 17 mph.

    Low: 69 °F

    Mostly Cloudy

  • Thursday

    Thursday: Showers likely, mainly after 5pm. Cloudy, with a high near 81. Southwest wind 10 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 81 °F

    Mostly Cloudy
    then Showers
    Likely

  • Thursday Night

    Thursday Night: Showers. Low around 62. West wind 5 to 10 mph becoming north after midnight. Chance of precipitation is 90%. New precipitation amounts between a half and three quarters of an inch possible.

    Low: 62 °F

    Showers

  • Friday

    Friday: A 40 percent chance of showers before 1pm. Cloudy through mid morning, then gradual clearing, with a high near 71. North northeast wind around 14 mph, with gusts as high as 20 mph.

    High: 71 °F

    Chance
    Showers

  • Friday Night

    Friday Night: Mostly clear, with a low around 51. Northeast wind 7 to 10 mph, with gusts as high as 15 mph.

    Low: 51 °F

    Mostly Clear

  • Saturday

    Saturday: Sunny, with a high near 71.

    High: 71 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 49.

    Low: 49 °F

    Partly Cloudy

Detailed Forecast

Overnight
A 20 percent chance of showers before 5am. Cloudy, with a low around 62. South wind around 8 mph, with gusts as high as 15 mph.
Wednesday
A slight chance of showers between 7am and 11am. Mostly cloudy, with a high near 83. South wind around 9 mph, with gusts as high as 15 mph. Chance of precipitation is 20%.
Wednesday Night
Mostly cloudy, with a low around 69. South wind 7 to 11 mph, with gusts as high as 17 mph.
Thursday
Showers likely, mainly after 5pm. Cloudy, with a high near 81. Southwest wind 10 to 14 mph, with gusts as high as 23 mph. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.
Thursday Night
Showers. Low around 62. West wind 5 to 10 mph becoming north after midnight. Chance of precipitation is 90%. New precipitation amounts between a half and three quarters of an inch possible.
Friday
A 40 percent chance of showers before 1pm. Cloudy through mid morning, then gradual clearing, with a high near 71. North northeast wind around 14 mph, with gusts as high as 20 mph.
Friday Night
Mostly clear, with a low around 51. Northeast wind 7 to 10 mph, with gusts as high as 15 mph.
Saturday
Sunny, with a high near 71.
Saturday Night
Partly cloudy, with a low around 49.
Sunday
Sunny, with a high near 72.
Sunday Night
Mostly clear, with a low around 46.
Monday
Sunny, with a high near 66.
Monday Night
Clear, with a low around 43.
Tuesday
Sunny, with a high near 68.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Harristown IL
 39.84°N 89.06°W (Elev. 699 ft)
Last Update:
3:15 am CDT Sep 30, 2026
Forecast Valid:
4am CDT Sep 30, 2026-6pm CDT Oct 6, 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