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.

Overcast

38°F

3°C

Humidity 89%
Wind Speed NE 15 mph
Barometer 30.36 in (1028.2 mb)
Dewpoint 35°F (2°C)
Visibility 10.00 mi
Wind Chill29°F (-2°C)
Last update 6 Mar 12:56 pm EST
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Cloudy, with a high near 40. Northeast wind 6 to 9 mph.

    High: 40 °F

    Cloudy

  • Tonight

    Tonight: A slight chance of drizzle after 4am. Cloudy, with a low around 33. Light northeast wind.

    Low: 33 °F

    Cloudy then
    Slight Chance
    Drizzle

  • Saturday

    Saturday: Cloudy, with a high near 49. Calm wind becoming south 5 to 7 mph in the morning.

    High: 49 °F

    Cloudy

  • Saturday Night

    Saturday Night: A chance of showers and thunderstorms, then showers likely after 1am. Areas of dense fog after 1am. Otherwise, cloudy, with a low around 43. Southwest wind 6 to 9 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    Low: 43 °F

    Chance
    Showers then
    Showers
    Likely and
    Areas Dense
    Fog

  • Sunday

    Sunday: A 30 percent chance of showers before 1pm. Areas of fog before 1pm. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 57. West wind 7 to 10 mph.

    High: 57 °F

    Chance
    Showers and
    Areas Fog

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 38.

    Low: 38 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 56.

    High: 56 °F

    Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 41.

    Low: 41 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 57.

    High: 57 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
Cloudy, with a high near 40. Northeast wind 6 to 9 mph.
Tonight
A slight chance of drizzle after 4am. Cloudy, with a low around 33. Light northeast wind.
Saturday
Cloudy, with a high near 49. Calm wind becoming south 5 to 7 mph in the morning.
Saturday Night
A chance of showers and thunderstorms, then showers likely after 1am. Areas of dense fog after 1am. Otherwise, cloudy, with a low around 43. Southwest wind 6 to 9 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Sunday
A 30 percent chance of showers before 1pm. Areas of fog before 1pm. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 57. West wind 7 to 10 mph.
Sunday Night
Mostly clear, with a low around 38.
Monday
Sunny, with a high near 56.
Monday Night
Partly cloudy, with a low around 41.
Tuesday
Mostly sunny, with a high near 57.
Tuesday Night
A 30 percent chance of rain after 1am. Mostly cloudy, with a low around 41.
Wednesday
A 50 percent chance of rain. Cloudy, with a high near 53.
Wednesday Night
Rain likely. Cloudy, with a low around 37. Chance of precipitation is 60%.
Thursday
A 40 percent chance of rain. Mostly cloudy, with a high near 46.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
12:51 pm EST Mar 6, 2026
Forecast Valid:
1pm EST Mar 6, 2026-6pm EDT Mar 12, 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