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

55°F

13°C

Humidity 96%
Wind Speed Calm
Barometer 29.99 in (1015.5 mb)
Dewpoint 54°F (12°C)
Visibility 10.00 mi
Last update 13 Oct 7:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Patchy fog before 9am. Otherwise, partly sunny, with a high near 68. Light and variable wind becoming south 5 to 9 mph in the morning.

    High: 68 °F

    Patchy Fog
    then Partly
    Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 63. Southwest wind around 10 mph, with gusts as high as 20 mph.

    Low: 63 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Mostly sunny, with a high near 76. West wind around 10 mph.

    High: 76 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 55. North wind 6 to 10 mph.

    Low: 55 °F

    Partly Cloudy

  • Thursday

    Thursday: Sunny, with a high near 63. North wind 5 to 10 mph.

    High: 63 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers likely after 2am. Increasing clouds, with a low around 51. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 51 °F

    Partly Cloudy
    then Showers
    Likely

  • Friday

    Friday: Showers. High near 68. Chance of precipitation is 90%.

    High: 68 °F

    Showers

  • Friday Night

    Friday Night: Showers likely before 8pm. Partly cloudy, with a low around 44. Breezy. Chance of precipitation is 60%.

    Low: 44 °F

    Breezy.
    Showers
    Likely then
    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 53. Breezy.

    High: 53 °F

    Sunny and
    Breezy

Detailed Forecast

Today
Patchy fog before 9am. Otherwise, partly sunny, with a high near 68. Light and variable wind becoming south 5 to 9 mph in the morning.
Tonight
Partly cloudy, with a low around 63. Southwest wind around 10 mph, with gusts as high as 20 mph.
Wednesday
Mostly sunny, with a high near 76. West wind around 10 mph.
Wednesday Night
Partly cloudy, with a low around 55. North wind 6 to 10 mph.
Thursday
Sunny, with a high near 63. North wind 5 to 10 mph.
Thursday Night
Showers likely after 2am. Increasing clouds, with a low around 51. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday
Showers. High near 68. Chance of precipitation is 90%.
Friday Night
Showers likely before 8pm. Partly cloudy, with a low around 44. Breezy. Chance of precipitation is 60%.
Saturday
Sunny, with a high near 53. Breezy.
Saturday Night
Mostly clear, with a low around 39.
Sunday
Sunny, with a high near 54.
Sunday Night
Mostly clear, with a low around 44.
Monday
Mostly sunny, with a high near 60.
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
2:02 am EDT Oct 13, 2026
Forecast Valid:
8am EDT Oct 13, 2026-6pm EDT Oct 19, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

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