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

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

A Few Clouds

27°F

-3°C

Humidity 43%
Wind Speed W 18 mph
Barometer 29.85 in (1010.8 mb)
Dewpoint 7°F (-14°C)
Visibility 10.00 mi
Wind Chill14°F (-10°C)
Last update 16 Jan 10:56 am EST
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Sunny, with a high near 35. Wind chill values between 15 and 25. Breezy, with a west wind 16 to 22 mph.

    High: 35 °F

    Sunny and
    Breezy

  • Tonight

    Tonight: A 30 percent chance of snow after 1am. Mostly cloudy, with a low around 32. Wind chill values between 25 and 30. South wind 9 to 14 mph.

    Low: 32 °F

    Mostly Cloudy
    then Chance
    Snow

  • Saturday

    Saturday: Rain likely, possibly mixed with snow. Mostly cloudy, with a steady temperature around 37. Southwest wind 9 to 11 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.

    High: 37 °F

    Rain/Snow
    Likely

  • Saturday Night

    Saturday Night: A slight chance of snow before 7pm, then a slight chance of snow after 1am. Mostly cloudy, with a low around 33. West wind 8 to 11 mph. Chance of precipitation is 20%.

    Low: 33 °F

    Mostly Cloudy
    then Slight
    Chance Snow

  • Sunday

    Sunday: A slight chance of snow before 10am, then a slight chance of rain between 10am and 1pm, then a chance of snow after 1pm. Cloudy, with a high near 36. West wind 8 to 10 mph. Chance of precipitation is 30%.

    High: 36 °F

    Chance
    Rain/Snow

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 26.

    Low: 26 °F

    Partly Cloudy

  • M.L.King Day

    M.L.King Day: Sunny, with a high near 33. Breezy.

    High: 33 °F

    Sunny then
    Mostly Sunny
    and Breezy

  • Monday Night

    Monday Night: Mostly clear, with a low around 18. Windy.

    Low: 18 °F

    Mostly Clear
    and Windy

  • Tuesday

    Tuesday: Sunny, with a high near 23. Breezy.

    High: 23 °F

    Sunny and
    Breezy

Detailed Forecast

Today
Sunny, with a high near 35. Wind chill values between 15 and 25. Breezy, with a west wind 16 to 22 mph.
Tonight
A 30 percent chance of snow after 1am. Mostly cloudy, with a low around 32. Wind chill values between 25 and 30. South wind 9 to 14 mph.
Saturday
Rain likely, possibly mixed with snow. Mostly cloudy, with a steady temperature around 37. Southwest wind 9 to 11 mph. Chance of precipitation is 60%. New snow accumulation of less than a half inch possible.
Saturday Night
A slight chance of snow before 7pm, then a slight chance of snow after 1am. Mostly cloudy, with a low around 33. West wind 8 to 11 mph. Chance of precipitation is 20%.
Sunday
A slight chance of snow before 10am, then a slight chance of rain between 10am and 1pm, then a chance of snow after 1pm. Cloudy, with a high near 36. West wind 8 to 10 mph. Chance of precipitation is 30%.
Sunday Night
Partly cloudy, with a low around 26.
M.L.King Day
Sunny, with a high near 33. Breezy.
Monday Night
Mostly clear, with a low around 18. Windy.
Tuesday
Sunny, with a high near 23. Breezy.
Tuesday Night
Mostly clear, with a low around 17. Breezy.
Wednesday
Mostly sunny, with a high near 32.
Wednesday Night
Mostly cloudy, with a low around 28.
Thursday
Partly sunny, with a high near 37.
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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:
11:24 am EST Jan 16, 2026
Forecast Valid:
11am EST Jan 16, 2026-6pm EST Jan 22, 2026
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation