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

74°F

23°C

Humidity 52%
Wind Speed NW 9 mph
Barometer 30.04 in (1016.9 mb)
Dewpoint 55°F (13°C)
Visibility 10.00 mi
Last update 19 Jun 10:54 am CDT
Extended Forecast for

Harristown IL

  • Juneteenth

    Juneteenth: Mostly sunny, with a high near 79. West northwest wind around 9 mph.

    High: 79 °F

    Mostly Sunny

  • Tonight

    Tonight: Mostly cloudy, with a low around 60. West northwest wind around 5 mph becoming calm in the evening.

    Low: 60 °F

    Mostly Cloudy

  • Saturday

    Saturday: Partly sunny, then gradually becoming sunny, with a high near 80. Light and variable wind becoming west 5 to 7 mph in the morning.

    High: 80 °F

    Becoming
    Sunny

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 62. Calm wind becoming east southeast 5 to 7 mph after midnight.

    Low: 62 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Showers, with thunderstorms also possible after 1pm. Some of the storms could produce heavy rainfall. High near 77. East southeast wind 9 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.

    High: 77 °F

    Heavy Rain

  • Sunday Night

    Sunday Night: Showers and possibly a thunderstorm. Low around 61. South wind 16 to 18 mph becoming north after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 90%. New precipitation amounts between three quarters and one inch possible.

    Low: 61 °F

    Showers

  • Monday

    Monday: Partly sunny, with a high near 74. North northeast wind around 15 mph, with gusts as high as 21 mph.

    High: 74 °F

    Partly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 55.

    Low: 55 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 76.

    High: 76 °F

    Mostly Sunny

Detailed Forecast

Juneteenth
Mostly sunny, with a high near 79. West northwest wind around 9 mph.
Tonight
Mostly cloudy, with a low around 60. West northwest wind around 5 mph becoming calm in the evening.
Saturday
Partly sunny, then gradually becoming sunny, with a high near 80. Light and variable wind becoming west 5 to 7 mph in the morning.
Saturday Night
Increasing clouds, with a low around 62. Calm wind becoming east southeast 5 to 7 mph after midnight.
Sunday
Showers, with thunderstorms also possible after 1pm. Some of the storms could produce heavy rainfall. High near 77. East southeast wind 9 to 18 mph, with gusts as high as 25 mph. Chance of precipitation is 100%. New rainfall amounts between 1 and 2 inches possible.
Sunday Night
Showers and possibly a thunderstorm. Low around 61. South wind 16 to 18 mph becoming north after midnight. Winds could gust as high as 22 mph. Chance of precipitation is 90%. New precipitation amounts between three quarters and one inch possible.
Monday
Partly sunny, with a high near 74. North northeast wind around 15 mph, with gusts as high as 21 mph.
Monday Night
Partly cloudy, with a low around 55.
Tuesday
Mostly sunny, with a high near 76.
Tuesday Night
Partly cloudy, with a low around 58.
Wednesday
Sunny, with a high near 78.
Wednesday Night
Mostly clear, with a low around 59.
Thursday
Mostly sunny, with a high near 78.
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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:
8:06 am CDT Jun 19, 2026
Forecast Valid:
11am CDT Jun 19, 2026-6pm CDT Jun 25, 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