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

64°F

18°C

Humidity 56%
Wind Speed S 9 mph
Barometer 30.00 in (1015.8 mb)
Dewpoint 48°F (9°C)
Visibility 10.00 mi
Last update 10 Mar 12:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Sunny, with a high near 63. South wind around 9 mph.

    High: 63 °F

    Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 40. South wind around 5 mph becoming calm in the evening.

    Low: 40 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Partly sunny, with a high near 59. South wind 3 to 8 mph.

    High: 59 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: A chance of rain before 11pm, then a chance of showers and thunderstorms between 11pm and 2am, then a chance of rain after 2am. Mostly cloudy, with a low around 48. Southwest wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 40%.

    Low: 48 °F

    Chance
    Showers

  • Thursday

    Thursday: A chance of rain before 5pm, then a chance of rain and snow showers. Mostly cloudy, with a temperature falling to around 41 by 5pm. Northwest wind 11 to 15 mph. Chance of precipitation is 50%.

    High: 48 °F⇓

    Chance Rain
    then Chance
    Rain/Snow

  • Thursday Night

    Thursday Night: A chance of rain and snow showers before 8pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 30. Chance of precipitation is 30%.

    Low: 30 °F

    Chance
    Rain/Snow
    then Mostly
    Clear

  • Friday

    Friday: Increasing clouds, with a high near 45.

    High: 45 °F

    Increasing
    Clouds

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 35.

    Low: 35 °F

    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 46.

    High: 46 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
Sunny, with a high near 63. South wind around 9 mph.
Tonight
Partly cloudy, with a low around 40. South wind around 5 mph becoming calm in the evening.
Wednesday
Partly sunny, with a high near 59. South wind 3 to 8 mph.
Wednesday Night
A chance of rain before 11pm, then a chance of showers and thunderstorms between 11pm and 2am, then a chance of rain after 2am. Mostly cloudy, with a low around 48. Southwest wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 40%.
Thursday
A chance of rain before 5pm, then a chance of rain and snow showers. Mostly cloudy, with a temperature falling to around 41 by 5pm. Northwest wind 11 to 15 mph. Chance of precipitation is 50%.
Thursday Night
A chance of rain and snow showers before 8pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 30. Chance of precipitation is 30%.
Friday
Increasing clouds, with a high near 45.
Friday Night
Mostly cloudy, with a low around 35.
Saturday
Mostly sunny, with a high near 46.
Saturday Night
Mostly cloudy, with a low around 34.
Sunday
Cloudy, with a high near 49.
Sunday Night
Rain. Low around 40. Chance of precipitation is 80%.
Monday
Rain. High near 50. Chance of precipitation is 80%.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
10:53 am EDT Mar 10, 2026
Forecast Valid:
1pm EDT Mar 10, 2026-6pm EDT Mar 16, 2026
 
Forecast Discussion
 
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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