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

19°F

-7°C

Humidity 71%
Wind Speed SW 7 mph
Barometer 30.23 in (1024.6 mb)
Dewpoint 11°F (-12°C)
Visibility 10.00 mi
Wind Chill10°F (-12°C)
Last update 24 Feb 1:54 am CST
Extended Forecast for

Harristown IL

  • Overnight

    Overnight: Mostly cloudy, with a low around 19. South wind 6 to 10 mph, with gusts as high as 17 mph.

    Low: 19 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: Mostly cloudy, with a high near 46. Breezy, with a south wind 11 to 16 mph increasing to 19 to 24 mph in the afternoon. Winds could gust as high as 36 mph.

    High: 46 °F

    Mostly Cloudy
    and Breezy

  • Tuesday Night

    Tuesday Night: Cloudy, then gradually becoming partly cloudy, with a low around 29. South southwest wind 9 to 15 mph becoming northwest after midnight. Winds could gust as high as 23 mph.

    Low: 29 °F

    Decreasing
    Clouds

  • Wednesday

    Wednesday: Mostly sunny, with a high near 45. West northwest wind 7 to 11 mph, with gusts as high as 17 mph.

    High: 45 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Rain and snow likely, becoming all snow after 3am. Mostly cloudy, with a low around 29. North wind 7 to 11 mph becoming east northeast after midnight. Winds could gust as high as 15 mph. Chance of precipitation is 70%. New snow accumulation of less than one inch possible.

    Low: 29 °F

    Rain/Snow
    Likely

  • Thursday

    Thursday: A chance of snow before 9am, then a chance of rain between 9am and noon. Mostly cloudy, then gradually becoming sunny, with a high near 44. East northeast wind 8 to 11 mph becoming north northwest in the afternoon. Winds could gust as high as 15 mph. Chance of precipitation is 30%.

    High: 44 °F

    Chance
    Rain/Snow
    then Mostly
    Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 28. North northwest wind 5 to 8 mph becoming light and variable.

    Low: 28 °F

    Mostly Clear

  • Friday

    Friday: Sunny, with a high near 57.

    High: 57 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 35.

    Low: 35 °F

    Mostly Clear

Detailed Forecast

Overnight
Mostly cloudy, with a low around 19. South wind 6 to 10 mph, with gusts as high as 17 mph.
Tuesday
Mostly cloudy, with a high near 46. Breezy, with a south wind 11 to 16 mph increasing to 19 to 24 mph in the afternoon. Winds could gust as high as 36 mph.
Tuesday Night
Cloudy, then gradually becoming partly cloudy, with a low around 29. South southwest wind 9 to 15 mph becoming northwest after midnight. Winds could gust as high as 23 mph.
Wednesday
Mostly sunny, with a high near 45. West northwest wind 7 to 11 mph, with gusts as high as 17 mph.
Wednesday Night
Rain and snow likely, becoming all snow after 3am. Mostly cloudy, with a low around 29. North wind 7 to 11 mph becoming east northeast after midnight. Winds could gust as high as 15 mph. Chance of precipitation is 70%. New snow accumulation of less than one inch possible.
Thursday
A chance of snow before 9am, then a chance of rain between 9am and noon. Mostly cloudy, then gradually becoming sunny, with a high near 44. East northeast wind 8 to 11 mph becoming north northwest in the afternoon. Winds could gust as high as 15 mph. Chance of precipitation is 30%.
Thursday Night
Mostly clear, with a low around 28. North northwest wind 5 to 8 mph becoming light and variable.
Friday
Sunny, with a high near 57.
Friday Night
Mostly clear, with a low around 35.
Saturday
Mostly sunny, with a high near 56.
Saturday Night
Partly cloudy, with a low around 25.
Sunday
A chance of rain and snow. Partly sunny, with a high near 40.
Sunday Night
A chance of snow. Mostly cloudy, with a low around 26.
Monday
A chance of rain and snow. Partly sunny, with a high near 41.
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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:
1:26 am CST Feb 24, 2026
Forecast Valid:
2am CST Feb 24, 2026-6pm CST Mar 2, 2026
 
Forecast Discussion
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation