National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Fair

16°F

-9°C

Humidity 47%
Wind Speed W 7 mph
Barometer 30.50 in (1032.9 mb)
Dewpoint -1°F (-18°C)
Visibility 10.00 mi
Wind Chill6°F (-14°C)
Last update 21 Jan 12:56 am EST
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: Mostly clear, with a low around 18. Wind chill values between 5 and 10. West wind 10 to 13 mph.

    Low: 18 °F

    Mostly Clear

  • Wednesday

    Wednesday: Increasing clouds, with a high near 37. Wind chill values between 5 and 15. Southwest wind 9 to 15 mph.

    High: 37 °F

    Increasing
    Clouds

  • Wednesday Night

    Wednesday Night: A chance of rain and snow before 1am, then a slight chance of snow between 1am and 4am. Cloudy, then gradually becoming partly cloudy, with a temperature rising to around 38 by 8pm. Wind chill values between 25 and 30. Southwest wind 16 to 18 mph. Chance of precipitation is 30%.

    Low: 35 °F⇑

    Chance
    Rain/Snow

  • Thursday

    Thursday: Mostly sunny, with a high near 41. Southwest wind 16 to 18 mph.

    High: 41 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 29. West wind 14 to 17 mph.

    Low: 29 °F

    Partly Cloudy

  • Friday

    Friday: Partly sunny, with a high near 32. Breezy.

    High: 32 °F

    Partly Sunny
    then Mostly
    Cloudy and
    Breezy

  • Friday Night

    Friday Night: Partly cloudy, with a low around 11. Breezy.

    Low: 11 °F

    Partly Cloudy
    and Breezy

  • Saturday

    Saturday: Partly sunny and cold, with a high near 17.

    High: 17 °F

    Cold

  • Saturday Night

    Saturday Night: A 40 percent chance of snow after 1am. Mostly cloudy, with a low around 13.

    Low: 13 °F

    Mostly Cloudy
    then Chance
    Snow

Detailed Forecast

Overnight
Mostly clear, with a low around 18. Wind chill values between 5 and 10. West wind 10 to 13 mph.
Wednesday
Increasing clouds, with a high near 37. Wind chill values between 5 and 15. Southwest wind 9 to 15 mph.
Wednesday Night
A chance of rain and snow before 1am, then a slight chance of snow between 1am and 4am. Cloudy, then gradually becoming partly cloudy, with a temperature rising to around 38 by 8pm. Wind chill values between 25 and 30. Southwest wind 16 to 18 mph. Chance of precipitation is 30%.
Thursday
Mostly sunny, with a high near 41. Southwest wind 16 to 18 mph.
Thursday Night
Partly cloudy, with a low around 29. West wind 14 to 17 mph.
Friday
Partly sunny, with a high near 32. Breezy.
Friday Night
Partly cloudy, with a low around 11. Breezy.
Saturday
Partly sunny and cold, with a high near 17.
Saturday Night
A 40 percent chance of snow after 1am. Mostly cloudy, with a low around 13.
Sunday
Snow likely. Mostly cloudy, with a high near 21. Chance of precipitation is 70%.
Sunday Night
Snow likely. Cloudy, with a low around 18. Chance of precipitation is 60%.
Monday
A 40 percent chance of snow. Partly sunny, with a high near 26.
Monday Night
Partly cloudy, with a low around 17.
Tuesday
Mostly sunny, with a high near 25.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
1:12 am EST Jan 21, 2026
Forecast Valid:
1am EST Jan 21, 2026-6pm EST Jan 27, 2026
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation