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

46°F

8°C

Humidity 47%
Wind Speed N 20 G 26 mph
Barometer 30.04 in (1017.2 mb)
Dewpoint 27°F (-3°C)
Visibility 10.00 mi
Wind Chill38°F (3°C)
Last update 27 Mar 2:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: A 20 percent chance of snow showers after 2am. Mostly cloudy, with a low around 33. Wind chill values between 25 and 30. North wind 6 to 13 mph.

    Low: 33 °F

    Mostly Cloudy
    then Slight
    Chance Snow
    Showers

  • Saturday

    Saturday: Mostly cloudy, then gradually becoming sunny, with a high near 39. Wind chill values between 20 and 30. Northwest wind 15 to 18 mph.

    High: 39 °F

    Decreasing
    Clouds

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 30. Northwest wind 5 to 14 mph.

    Low: 30 °F

    Partly Cloudy

  • Sunday

    Sunday: Mostly sunny, with a high near 45. South wind 7 to 17 mph.

    High: 45 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Mostly cloudy, with a low around 42. Southwest wind 15 to 18 mph.

    Low: 42 °F

    Mostly Cloudy

  • Monday

    Monday: Partly sunny, with a high near 53.

    High: 53 °F

    Partly Sunny

  • Monday Night

    Monday Night: A 30 percent chance of rain after 2am. Mostly cloudy, with a low around 46.

    Low: 46 °F

    Mostly Cloudy
    then Chance
    Rain

  • Tuesday

    Tuesday: A 30 percent chance of rain before 2pm. Partly sunny, with a high near 58.

    High: 58 °F

    Chance Rain

  • Tuesday Night

    Tuesday Night: A chance of rain between 8pm and 2am. Mostly cloudy, with a low around 50. Breezy. Chance of precipitation is 30%.

    Low: 50 °F

    Chance Rain
    and Breezy

Detailed Forecast

Tonight
A 20 percent chance of snow showers after 2am. Mostly cloudy, with a low around 33. Wind chill values between 25 and 30. North wind 6 to 13 mph.
Saturday
Mostly cloudy, then gradually becoming sunny, with a high near 39. Wind chill values between 20 and 30. Northwest wind 15 to 18 mph.
Saturday Night
Partly cloudy, with a low around 30. Northwest wind 5 to 14 mph.
Sunday
Mostly sunny, with a high near 45. South wind 7 to 17 mph.
Sunday Night
Mostly cloudy, with a low around 42. Southwest wind 15 to 18 mph.
Monday
Partly sunny, with a high near 53.
Monday Night
A 30 percent chance of rain after 2am. Mostly cloudy, with a low around 46.
Tuesday
A 30 percent chance of rain before 2pm. Partly sunny, with a high near 58.
Tuesday Night
A chance of rain between 8pm and 2am. Mostly cloudy, with a low around 50. Breezy. Chance of precipitation is 30%.
Wednesday
A 40 percent chance of rain after 2pm. Partly sunny, with a high near 62.
Wednesday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 42.
Thursday
A 40 percent chance of rain. Mostly cloudy, with a high near 49.
Thursday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 39.
Friday
A 50 percent chance of rain. Cloudy, with a high near 45. Breezy.
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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:
3:17 pm EDT Mar 27, 2026
Forecast Valid:
3pm EDT Mar 27, 2026-6pm EDT Apr 3, 2026
 
Forecast Discussion
 
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Additional Resources

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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