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

20°F

-7°C

Humidity 48%
Wind Speed N 7 mph
Barometer 30.61 in (1036.5 mb)
Dewpoint 3°F (-16°C)
Visibility 10.00 mi
Wind Chill11°F (-12°C)
Last update 2 Mar 5:56 am EST
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Mostly sunny, with a high near 28. Wind chill values between 10 and 20. North wind 5 to 9 mph becoming light and variable in the afternoon.

    High: 28 °F

    Mostly Sunny

  • Tonight

    Tonight: Mostly clear, with a low around 22. South wind around 5 mph.

    Low: 22 °F

    Mostly Clear

  • Tuesday

    Tuesday: Rain, possibly mixed with snow, becoming all rain after 4pm. High near 39. Wind chill values between 20 and 30. Southeast wind 5 to 7 mph. Chance of precipitation is 90%. New snow accumulation of less than a half inch possible.

    High: 39 °F

    Rain/Snow
    Likely then
    Rain/Snow

  • Tuesday Night

    Tuesday Night: Rain. Low around 37. South wind 7 to 9 mph becoming west after midnight. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 37 °F

    Rain

  • Wednesday

    Wednesday: A 20 percent chance of rain. Partly sunny, with a steady temperature around 40. West wind 6 to 10 mph becoming southeast in the afternoon.

    High: 40 °F

    Slight Chance
    Rain

  • Wednesday Night

    Wednesday Night: A 50 percent chance of rain. Cloudy, with a low around 39.

    Low: 39 °F

    Chance Rain

  • Thursday

    Thursday: A 40 percent chance of rain. Cloudy, with a high near 48.

    High: 48 °F

    Chance Rain

  • Thursday Night

    Thursday Night: A 50 percent chance of rain. Cloudy, with a low around 39.

    Low: 39 °F

    Chance Rain

  • Friday

    Friday: A 40 percent chance of rain before 1pm. Cloudy, with a high near 43.

    High: 43 °F

    Chance Rain

Detailed Forecast

Today
Mostly sunny, with a high near 28. Wind chill values between 10 and 20. North wind 5 to 9 mph becoming light and variable in the afternoon.
Tonight
Mostly clear, with a low around 22. South wind around 5 mph.
Tuesday
Rain, possibly mixed with snow, becoming all rain after 4pm. High near 39. Wind chill values between 20 and 30. Southeast wind 5 to 7 mph. Chance of precipitation is 90%. New snow accumulation of less than a half inch possible.
Tuesday Night
Rain. Low around 37. South wind 7 to 9 mph becoming west after midnight. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.
Wednesday
A 20 percent chance of rain. Partly sunny, with a steady temperature around 40. West wind 6 to 10 mph becoming southeast in the afternoon.
Wednesday Night
A 50 percent chance of rain. Cloudy, with a low around 39.
Thursday
A 40 percent chance of rain. Cloudy, with a high near 48.
Thursday Night
A 50 percent chance of rain. Cloudy, with a low around 39.
Friday
A 40 percent chance of rain before 1pm. Cloudy, with a high near 43.
Friday Night
Cloudy, with a low around 38.
Saturday
Cloudy, with a high near 49.
Saturday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 43.
Sunday
Mostly cloudy, with a high near 50.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
2:30 am EST Mar 2, 2026
Forecast Valid:
6am EST Mar 2, 2026-6pm EDT Mar 8, 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