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.

Mostly Cloudy

38°F

3°C

Humidity 65%
Wind Speed S 9 mph
Barometer 29.87 in (1011.4 mb)
Dewpoint 27°F (-3°C)
Visibility 10.00 mi
Wind Chill32°F (0°C)
Last update 26 Feb 1:56 pm EST
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: A slight chance of rain and snow showers after 4pm. Mostly cloudy, with a high near 36. Southwest wind around 6 mph. Chance of precipitation is 20%.

    High: 36 °F

    Slight Chance
    Rain/Snow

  • Tonight

    Tonight: Cloudy during the early evening, then gradual clearing, with a low around 27. Light and variable wind becoming north around 6 mph in the evening.

    Low: 27 °F

    Gradual
    Clearing

  • Friday

    Friday: Sunny, with a high near 37. Wind chill values between 25 and 30. Calm wind becoming southwest around 6 mph in the afternoon.

    High: 37 °F

    Sunny

  • Friday Night

    Friday Night: Mostly clear, with a low around 32. South wind around 6 mph.

    Low: 32 °F

    Mostly Clear

  • Saturday

    Saturday: Mostly sunny, with a high near 42. South wind around 7 mph.

    High: 42 °F

    Mostly Sunny

  • Saturday Night

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

    Low: 31 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 35.

    High: 35 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 20.

    Low: 20 °F

    Partly Cloudy

  • Monday

    Monday: A 30 percent chance of snow after 1pm. Partly sunny, with a high near 28.

    High: 28 °F

    Mostly Sunny
    then Chance
    Snow

Detailed Forecast

This Afternoon
A slight chance of rain and snow showers after 4pm. Mostly cloudy, with a high near 36. Southwest wind around 6 mph. Chance of precipitation is 20%.
Tonight
Cloudy during the early evening, then gradual clearing, with a low around 27. Light and variable wind becoming north around 6 mph in the evening.
Friday
Sunny, with a high near 37. Wind chill values between 25 and 30. Calm wind becoming southwest around 6 mph in the afternoon.
Friday Night
Mostly clear, with a low around 32. South wind around 6 mph.
Saturday
Mostly sunny, with a high near 42. South wind around 7 mph.
Saturday Night
Partly cloudy, with a low around 31.
Sunday
Partly sunny, with a high near 35.
Sunday Night
Partly cloudy, with a low around 20.
Monday
A 30 percent chance of snow after 1pm. Partly sunny, with a high near 28.
Monday Night
Partly cloudy, with a low around 23.
Tuesday
Partly sunny, with a high near 35.
Tuesday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 32.
Wednesday
A 40 percent chance of rain. Partly sunny, with a high near 42.
Wednesday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 33.
Thursday
A chance of rain. Mostly cloudy, with a high near 42.
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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:
12:59 pm EST Feb 26, 2026
Forecast Valid:
3pm EST Feb 26, 2026-6pm EST Mar 5, 2026
 
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Additional Resources

Radar & Satellite Image

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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