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

49°F

9°C

Humidity 93%
Wind Speed S 6 mph
Barometer 30.04 in (1017.4 mb)
Dewpoint 47°F (8°C)
Visibility 9.00 mi
Wind Chill46°F (8°C)
Last update 10 Mar 10:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Sunny, with a high near 60. Light southwest wind becoming south 5 to 9 mph in the afternoon.

    High: 60 °F

    Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 41. South wind 5 to 7 mph.

    Low: 41 °F

    Partly Cloudy

  • Wednesday

    Wednesday: Partly sunny, with a high near 57. Southeast wind 6 to 11 mph.

    High: 57 °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 49. Southwest wind 15 to 18 mph. Chance of precipitation is 40%.

    Low: 49 °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 4pm. Breezy, with a northwest wind around 20 mph. Chance of precipitation is 50%.

    High: 49 °F⇓

    Breezy.
    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 32. Chance of precipitation is 30%.

    Low: 32 °F

    Chance
    Rain/Snow
    then Mostly
    Clear

  • Friday

    Friday: Increasing clouds, with a high near 43. Breezy.

    High: 43 °F

    Sunny then
    Mostly Cloudy
    and Breezy

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 38. Breezy.

    Low: 38 °F

    Mostly Cloudy
    and Breezy

  • Saturday

    Saturday: Mostly sunny, with a high near 45. Breezy.

    High: 45 °F

    Mostly Sunny
    and Breezy
    then Sunny

Detailed Forecast

Today
Sunny, with a high near 60. Light southwest wind becoming south 5 to 9 mph in the afternoon.
Tonight
Partly cloudy, with a low around 41. South wind 5 to 7 mph.
Wednesday
Partly sunny, with a high near 57. Southeast wind 6 to 11 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 49. Southwest wind 15 to 18 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 4pm. Breezy, with a northwest wind around 20 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 32. Chance of precipitation is 30%.
Friday
Increasing clouds, with a high near 43. Breezy.
Friday Night
Mostly cloudy, with a low around 38. Breezy.
Saturday
Mostly sunny, with a high near 45. Breezy.
Saturday Night
Mostly cloudy, with a low around 36.
Sunday
Cloudy, with a high near 48.
Sunday Night
Rain. Low around 43. Windy. Chance of precipitation is 80%.
Monday
Rain. High near 49. Windy. Chance of precipitation is 80%.
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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:
10:53 am EDT Mar 10, 2026
Forecast Valid:
11am EDT Mar 10, 2026-6pm EDT Mar 16, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

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