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.

Light Drizzle Fog/Mist

35°F

2°C

Humidity 96%
Wind Speed N 7 mph
Barometer 29.84 in (1010.4 mb)
Dewpoint 34°F (1°C)
Visibility 2.50 mi
Wind Chill29°F (-2°C)
Last update 18 Feb 10:56 pm EST
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: A 40 percent chance of rain before 1am. Areas of fog before 1am. Otherwise, cloudy, with a steady temperature around 34. Northeast wind around 7 mph.

    Low: 34 °F

    Chance Rain
    and Areas Fog

  • Thursday

    Thursday: Mostly cloudy, with a high near 38. Northeast wind 6 to 8 mph.

    High: 38 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: A slight chance of rain and snow before 10pm, then a chance of rain. Mostly cloudy, with a low around 32. East wind 3 to 8 mph. Chance of precipitation is 50%.

    Low: 32 °F

    Slight Chance
    Rain/Snow
    then Chance
    Rain

  • Friday

    Friday: Rain. High near 38. East wind 9 to 13 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.

    High: 38 °F

    Rain

  • Friday Night

    Friday Night: Rain likely before 10pm, then a chance of rain and snow between 10pm and 4am, then a slight chance of rain after 4am. Cloudy, with a low around 33. Northeast wind 6 to 10 mph becoming north after midnight. Chance of precipitation is 60%. Little or no snow accumulation expected.

    Low: 33 °F

    Rain/Snow
    Likely

  • Saturday

    Saturday: A 30 percent chance of rain after 1pm. Partly sunny, with a high near 40.

    High: 40 °F

    Partly Sunny
    then Chance
    Rain

  • Saturday Night

    Saturday Night: A chance of rain before 1am, then a chance of rain and snow. Cloudy, with a low around 30. Chance of precipitation is 30%.

    Low: 30 °F

    Chance Rain
    then Chance
    Rain/Snow

  • Sunday

    Sunday: A 40 percent chance of snow. Mostly cloudy, with a high near 35.

    High: 35 °F

    Chance Snow

  • Sunday Night

    Sunday Night: A 50 percent chance of snow. Cloudy, with a low around 29. Blustery.

    Low: 29 °F

    Chance Snow
    and Blustery

Detailed Forecast

Tonight
A 40 percent chance of rain before 1am. Areas of fog before 1am. Otherwise, cloudy, with a steady temperature around 34. Northeast wind around 7 mph.
Thursday
Mostly cloudy, with a high near 38. Northeast wind 6 to 8 mph.
Thursday Night
A slight chance of rain and snow before 10pm, then a chance of rain. Mostly cloudy, with a low around 32. East wind 3 to 8 mph. Chance of precipitation is 50%.
Friday
Rain. High near 38. East wind 9 to 13 mph. Chance of precipitation is 90%. New precipitation amounts between a quarter and half of an inch possible.
Friday Night
Rain likely before 10pm, then a chance of rain and snow between 10pm and 4am, then a slight chance of rain after 4am. Cloudy, with a low around 33. Northeast wind 6 to 10 mph becoming north after midnight. Chance of precipitation is 60%. Little or no snow accumulation expected.
Saturday
A 30 percent chance of rain after 1pm. Partly sunny, with a high near 40.
Saturday Night
A chance of rain before 1am, then a chance of rain and snow. Cloudy, with a low around 30. Chance of precipitation is 30%.
Sunday
A 40 percent chance of snow. Mostly cloudy, with a high near 35.
Sunday Night
A 50 percent chance of snow. Cloudy, with a low around 29. Blustery.
Monday
A 40 percent chance of snow before 1pm. Mostly cloudy, with a high near 36. Breezy.
Monday Night
Partly cloudy, with a low around 25.
Tuesday
Sunny, with a high near 35.
Tuesday Night
Partly cloudy, with a low around 25.
Wednesday
Partly sunny, with a high near 39.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
12:48 pm EST Feb 18, 2026
Forecast Valid:
11pm EST Feb 18, 2026-6pm EST Feb 25, 2026
 
Forecast Discussion
 
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Additional Resources

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation