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

35°F

2°C

Humidity 85%
Wind Speed SW 14 G 24 mph
Barometer 29.69 in (1005.6 mb)
Dewpoint 31°F (-1°C)
Visibility 9.00 mi
Wind Chill26°F (-3°C)
Last update 25 Feb 11:56 am EST
Extended Forecast for

Port Jefferson NY

  • This Afternoon

    This Afternoon: Partly sunny, with a high near 38. Southwest wind 15 to 17 mph.

    High: 38 °F

    Partly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 32. Southwest wind around 14 mph.

    Low: 32 °F

    Partly Cloudy

  • Thursday

    Thursday: A 30 percent chance of snow after 1pm. Partly sunny, with a steady temperature around 33. Wind chill values between 25 and 30. West wind 7 to 10 mph.

    High: 33 °F

    Mostly Sunny
    then Chance
    Snow

  • Thursday Night

    Thursday Night: A 20 percent chance of snow before 1am. Mostly cloudy, with a low around 28. North wind around 6 mph.

    Low: 28 °F

    Slight Chance
    Snow

  • Friday

    Friday: Mostly sunny, with a high near 35. North wind around 6 mph becoming southwest in the afternoon.

    High: 35 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 30.

    Low: 30 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 42.

    High: 42 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 30.

    Low: 30 °F

    Partly Cloudy

  • Sunday

    Sunday: Partly sunny, with a high near 36.

    High: 36 °F

    Partly Sunny

Detailed Forecast

This Afternoon
Partly sunny, with a high near 38. Southwest wind 15 to 17 mph.
Tonight
Partly cloudy, with a low around 32. Southwest wind around 14 mph.
Thursday
A 30 percent chance of snow after 1pm. Partly sunny, with a steady temperature around 33. Wind chill values between 25 and 30. West wind 7 to 10 mph.
Thursday Night
A 20 percent chance of snow before 1am. Mostly cloudy, with a low around 28. North wind around 6 mph.
Friday
Mostly sunny, with a high near 35. North wind around 6 mph becoming southwest in the afternoon.
Friday Night
Partly cloudy, with a low around 30.
Saturday
Mostly sunny, with a high near 42.
Saturday Night
Partly cloudy, with a low around 30.
Sunday
Partly sunny, with a high near 36.
Sunday Night
Partly cloudy, with a low around 22.
Monday
A 40 percent chance of snow. Mostly cloudy, with a high near 28.
Monday Night
A 30 percent chance of snow. Mostly cloudy, with a low around 22.
Tuesday
A 30 percent chance of snow. Partly sunny, with a high near 33.
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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:
9:51 am EST Feb 25, 2026
Forecast Valid:
12pm EST Feb 25, 2026-6pm EST Mar 3, 2026
 
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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

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation