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

36°F

2°C

Humidity 48%
Wind Speed Calm
Barometer 30.31 in (1026.5 mb)
Dewpoint 18°F (-8°C)
Visibility 10.00 mi
Last update 1 Dec 6:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Increasing clouds, with a low around 33. North wind 5 to 8 mph becoming southeast after midnight.

    Low: 33 °F

    Increasing
    Clouds

  • Tuesday

    Tuesday: Rain. High near 45. East wind 7 to 16 mph becoming north in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 100%. New precipitation amounts between three quarters and one inch possible.

    High: 45 °F

    Rain

  • Tuesday Night

    Tuesday Night: Rain, mainly before 10pm. Low around 31. Wind chill values between 20 and 25. Blustery, with a northwest wind 18 to 22 mph, with gusts as high as 32 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 31 °F

    Blustery.
    Rain then
    Slight Chance
    Rain

  • Wednesday

    Wednesday: Sunny, with a high near 39. Wind chill values between 20 and 30. Northwest wind 6 to 14 mph, with gusts as high as 25 mph.

    High: 39 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 32. West wind 6 to 11 mph.

    Low: 32 °F

    Partly Cloudy

  • Thursday

    Thursday: Partly sunny, with a high near 40.

    High: 40 °F

    Partly Sunny

  • Thursday Night

    Thursday Night: Mostly clear, with a low around 20.

    Low: 20 °F

    Mostly Clear

  • Friday

    Friday: Mostly sunny, with a high near 36.

    High: 36 °F

    Mostly Sunny

  • Friday Night

    Friday Night: A chance of rain and snow after 1am. Mostly cloudy, with a low around 28. Chance of precipitation is 30%.

    Low: 28 °F

    Mostly Cloudy
    then Chance
    Rain/Snow

Detailed Forecast

Tonight
Increasing clouds, with a low around 33. North wind 5 to 8 mph becoming southeast after midnight.
Tuesday
Rain. High near 45. East wind 7 to 16 mph becoming north in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 100%. New precipitation amounts between three quarters and one inch possible.
Tuesday Night
Rain, mainly before 10pm. Low around 31. Wind chill values between 20 and 25. Blustery, with a northwest wind 18 to 22 mph, with gusts as high as 32 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Wednesday
Sunny, with a high near 39. Wind chill values between 20 and 30. Northwest wind 6 to 14 mph, with gusts as high as 25 mph.
Wednesday Night
Partly cloudy, with a low around 32. West wind 6 to 11 mph.
Thursday
Partly sunny, with a high near 40.
Thursday Night
Mostly clear, with a low around 20.
Friday
Mostly sunny, with a high near 36.
Friday Night
A chance of rain and snow after 1am. Mostly cloudy, with a low around 28. Chance of precipitation is 30%.
Saturday
A 30 percent chance of rain before 1pm. Partly sunny, with a high near 41.
Saturday Night
Mostly cloudy, with a low around 32.
Sunday
Partly sunny, with a high near 41.
Sunday Night
Mostly cloudy, with a low around 24.
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:
1:21 pm EST Dec 1, 2025
Forecast Valid:
7pm EST Dec 1, 2025-6pm EST Dec 8, 2025
 
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Additional Resources

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Hourly Weather Forecast

National Digital Forecast Database

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation