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.

Overcast

29°F

-2°C

Humidity 89%
Wind Speed NE 10 mph
Barometer 30.11 in (1019.7 mb)
Dewpoint 26°F (-3°C)
Visibility 10.00 mi
Wind Chill20°F (-7°C)
Last update 16 Feb 7:56 am EST
Extended Forecast for

Port Jefferson NY

  • Washington's Birthday

    Washington's Birthday: Mostly cloudy, then gradually becoming sunny, with a high near 36. Wind chill values between 20 and 30. Northeast wind 6 to 15 mph.

    High: 36 °F

    Decreasing
    Clouds

  • Tonight

    Tonight: A 20 percent chance of snow after 4am. Increasing clouds, with a low around 32. Calm wind.

    Low: 32 °F

    Partly Cloudy
    then Slight
    Chance Snow

  • Tuesday

    Tuesday: Cloudy, then gradually becoming mostly sunny, with a high near 39. Southwest wind 5 to 8 mph.

    High: 39 °F

    Decreasing
    Clouds

  • Tuesday Night

    Tuesday Night: Increasing clouds, with a low around 34. West wind 3 to 6 mph.

    Low: 34 °F

    Increasing
    Clouds

  • Wednesday

    Wednesday: Rain. High near 38. East wind 3 to 8 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 38 °F

    Rain

  • Wednesday Night

    Wednesday Night: Rain likely before 1am. Mostly cloudy, with a low around 36. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 36 °F

    Rain Likely

  • Thursday

    Thursday: Mostly cloudy, with a high near 38.

    High: 38 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: A chance of rain and snow after 1am. Mostly cloudy, with a low around 32. Chance of precipitation is 30%.

    Low: 32 °F

    Mostly Cloudy
    then Chance
    Rain/Snow

  • Friday

    Friday: A chance of rain and snow before 1pm, then rain likely. Mostly cloudy, with a high near 39. Chance of precipitation is 70%.

    High: 39 °F

    Rain/Snow
    Likely

Detailed Forecast

Washington's Birthday
Mostly cloudy, then gradually becoming sunny, with a high near 36. Wind chill values between 20 and 30. Northeast wind 6 to 15 mph.
Tonight
A 20 percent chance of snow after 4am. Increasing clouds, with a low around 32. Calm wind.
Tuesday
Cloudy, then gradually becoming mostly sunny, with a high near 39. Southwest wind 5 to 8 mph.
Tuesday Night
Increasing clouds, with a low around 34. West wind 3 to 6 mph.
Wednesday
Rain. High near 38. East wind 3 to 8 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Wednesday Night
Rain likely before 1am. Mostly cloudy, with a low around 36. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Thursday
Mostly cloudy, with a high near 38.
Thursday Night
A chance of rain and snow after 1am. Mostly cloudy, with a low around 32. Chance of precipitation is 30%.
Friday
A chance of rain and snow before 1pm, then rain likely. Mostly cloudy, with a high near 39. Chance of precipitation is 70%.
Friday Night
A chance of rain and snow. Cloudy, with a low around 34. Chance of precipitation is 50%.
Saturday
A 30 percent chance of rain. Mostly cloudy, with a high near 39.
Saturday Night
Mostly cloudy, with a low around 32.
Sunday
A chance of rain and snow. Mostly cloudy, with a high near 37. Chance of precipitation is 30%.
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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:
2:01 am EST Feb 16, 2026
Forecast Valid:
8am EST Feb 16, 2026-6pm EST Feb 22, 2026
 
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Additional Resources

Radar & Satellite Image

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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