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

27°F

-3°C

Humidity 35%
Wind Speed N 7 mph
Barometer 30.28 in (1025.5 mb)
Dewpoint 3°F (-16°C)
Visibility 10.00 mi
Wind Chill19°F (-7°C)
Last update 8 Dec 6:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Partly cloudy, with a low around 17. Wind chill values between 10 and 15. North wind 5 to 10 mph.

    Low: 17 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Increasing clouds, with a high near 37. Wind chill values between 10 and 20. Light and variable wind becoming south 5 to 8 mph in the afternoon.

    High: 37 °F

    Increasing
    Clouds

  • Tuesday Night

    Tuesday Night: A slight chance of rain and snow before 1am. Mostly cloudy, with a temperature rising to around 36 by 9pm. Southwest wind 10 to 16 mph. Chance of precipitation is 20%.

    Low: 33 °F⇑

    Slight Chance
    Rain/Snow

  • Wednesday

    Wednesday: Rain likely, mainly after 1pm. Mostly cloudy, with a high near 46. Breezy, with a southwest wind 11 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 46 °F

    Slight Chance
    Rain then
    Rain Likely
    and Breezy

  • Wednesday Night

    Wednesday Night: A 40 percent chance of rain before 1am. Cloudy, then gradually becoming partly cloudy, with a low around 34. Southwest wind 16 to 18 mph, with gusts as high as 29 mph.

    Low: 34 °F

    Chance Rain

  • Thursday

    Thursday: Mostly sunny, with a high near 41.

    High: 41 °F

    Mostly Sunny

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 27.

    Low: 27 °F

    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 36.

    High: 36 °F

    Mostly Sunny

  • Friday Night

    Friday Night: A 40 percent chance of snow. Mostly cloudy, with a low around 28.

    Low: 28 °F

    Chance Snow

Detailed Forecast

Tonight
Partly cloudy, with a low around 17. Wind chill values between 10 and 15. North wind 5 to 10 mph.
Tuesday
Increasing clouds, with a high near 37. Wind chill values between 10 and 20. Light and variable wind becoming south 5 to 8 mph in the afternoon.
Tuesday Night
A slight chance of rain and snow before 1am. Mostly cloudy, with a temperature rising to around 36 by 9pm. Southwest wind 10 to 16 mph. Chance of precipitation is 20%.
Wednesday
Rain likely, mainly after 1pm. Mostly cloudy, with a high near 46. Breezy, with a southwest wind 11 to 20 mph, with gusts as high as 30 mph. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Wednesday Night
A 40 percent chance of rain before 1am. Cloudy, then gradually becoming partly cloudy, with a low around 34. Southwest wind 16 to 18 mph, with gusts as high as 29 mph.
Thursday
Mostly sunny, with a high near 41.
Thursday Night
Partly cloudy, with a low around 27.
Friday
Mostly sunny, with a high near 36.
Friday Night
A 40 percent chance of snow. Mostly cloudy, with a low around 28.
Saturday
A chance of snow showers before 7am, then a chance of snow between 7am and noon. Partly sunny, with a high near 37. Chance of precipitation is 30%.
Saturday Night
Mostly cloudy, with a low around 25.
Sunday
Mostly sunny, with a high near 33.
Sunday Night
Mostly clear, with a low around 21.
Monday
Mostly sunny, with a high near 33.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
6:30 pm EST Dec 8, 2025
Forecast Valid:
7pm EST Dec 8, 2025-6pm EST Dec 15, 2025
 
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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