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.

Light Rain

45°F

7°C

Humidity 90%
Wind Speed S 6 mph
Barometer 29.51 in (999.3 mb)
Dewpoint 42°F (6°C)
Visibility 10.00 mi
Wind Chill42°F (6°C)
Last update 14 Jan 8:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: A 50 percent chance of rain. Cloudy, with a steady temperature around 43. South wind 7 to 9 mph.

    Low: 43 °F

    Chance Rain

  • Thursday

    Thursday: Cloudy, then gradually becoming mostly sunny, with a temperature falling to around 35 by 5pm. Wind chill values between 25 and 35. Breezy, with a west wind 8 to 13 mph increasing to 17 to 22 mph in the afternoon.

    High: 41 °F⇓

    Mostly Cloudy
    then Mostly
    Sunny and
    Breezy

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 25. Wind chill values between 10 and 20. Breezy, with a west wind 22 to 25 mph.

    Low: 25 °F

    Partly Cloudy
    and Breezy

  • Friday

    Friday: Sunny, with a high near 36. Wind chill values between 10 and 20. Breezy, with a west wind 15 to 23 mph.

    High: 36 °F

    Sunny and
    Breezy

  • Friday Night

    Friday Night: A 20 percent chance of snow after 1am. Mostly cloudy, with a low around 33. Southwest wind 10 to 14 mph.

    Low: 33 °F

    Mostly Cloudy
    then Slight
    Chance Snow

  • Saturday

    Saturday: A chance of rain and snow before 1pm, then a chance of rain. Mostly cloudy, with a high near 41. Chance of precipitation is 40%.

    High: 41 °F

    Chance
    Rain/Snow

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 31.

    Low: 31 °F

    Mostly Cloudy

  • Sunday

    Sunday: A 30 percent chance of snow after 1pm. Mostly cloudy, with a high near 33.

    High: 33 °F

    Mostly Cloudy
    then Chance
    Snow

  • Sunday Night

    Sunday Night: A 30 percent chance of snow before 1am. Partly cloudy, with a low around 24.

    Low: 24 °F

    Chance Snow

Detailed Forecast

Tonight
A 50 percent chance of rain. Cloudy, with a steady temperature around 43. South wind 7 to 9 mph.
Thursday
Cloudy, then gradually becoming mostly sunny, with a temperature falling to around 35 by 5pm. Wind chill values between 25 and 35. Breezy, with a west wind 8 to 13 mph increasing to 17 to 22 mph in the afternoon.
Thursday Night
Partly cloudy, with a low around 25. Wind chill values between 10 and 20. Breezy, with a west wind 22 to 25 mph.
Friday
Sunny, with a high near 36. Wind chill values between 10 and 20. Breezy, with a west wind 15 to 23 mph.
Friday Night
A 20 percent chance of snow after 1am. Mostly cloudy, with a low around 33. Southwest wind 10 to 14 mph.
Saturday
A chance of rain and snow before 1pm, then a chance of rain. Mostly cloudy, with a high near 41. Chance of precipitation is 40%.
Saturday Night
Mostly cloudy, with a low around 31.
Sunday
A 30 percent chance of snow after 1pm. Mostly cloudy, with a high near 33.
Sunday Night
A 30 percent chance of snow before 1am. Partly cloudy, with a low around 24.
M.L.King Day
Sunny, with a high near 31.
Monday Night
Partly cloudy, with a low around 21. Breezy.
Tuesday
Mostly sunny, with a high near 26. Breezy.
Tuesday Night
Partly cloudy, with a low around 18. Breezy.
Wednesday
Mostly sunny, with a high near 29.
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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:
2:31 pm EST Jan 14, 2026
Forecast Valid:
9pm EST Jan 14, 2026-6pm EST Jan 21, 2026
 
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Additional Resources

Radar & Satellite Image

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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