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

53°F

12°C

Humidity 86%
Wind Speed SW 17 G 25 mph
Barometer 29.77 in (1008.1 mb)
Dewpoint 49°F (9°C)
Visibility 10.00 mi
Wind Chill48°F (9°C)
Last update 11 Mar 7:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: A chance of showers and thunderstorms. Mostly cloudy, with a low around 48. Breezy, with a southwest wind around 21 mph. Chance of precipitation is 50%.

    Low: 48 °F

    Chance
    Showers and
    Breezy

  • Thursday

    Thursday: Rain showers before 5pm, then a chance of rain and snow showers. Temperature falling to around 38 by 3pm. Breezy, with a northwest wind 18 to 22 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.

    High: 50 °F⇓

    Breezy.
    Showers then
    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 33. Breezy, with a west wind 13 to 20 mph. Chance of precipitation is 30%.

    Low: 33 °F

    Chance
    Rain/Snow and
    Breezy then
    Mostly Clear

  • Friday

    Friday: Increasing clouds, with a high near 44. Breezy, with a west wind 6 to 11 mph becoming south 15 to 20 mph in the afternoon.

    High: 44 °F

    Mostly Sunny
    then Mostly
    Cloudy and
    Breezy

  • Friday Night

    Friday Night: Mostly cloudy, then gradually becoming mostly clear, with a low around 37. Breezy, with a south wind 20 to 24 mph.

    Low: 37 °F

    Decreasing
    Clouds and
    Breezy

  • Saturday

    Saturday: Sunny, with a high near 46. Windy.

    High: 46 °F

    Sunny and
    Windy

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 34.

    Low: 34 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Cloudy, with a high near 46.

    High: 46 °F

    Cloudy

  • Sunday Night

    Sunday Night: Showers, mainly after 2am. Low around 41. Breezy. Chance of precipitation is 80%.

    Low: 41 °F

    Breezy.
    Chance
    Showers then
    Showers

Detailed Forecast

Tonight
A chance of showers and thunderstorms. Mostly cloudy, with a low around 48. Breezy, with a southwest wind around 21 mph. Chance of precipitation is 50%.
Thursday
Rain showers before 5pm, then a chance of rain and snow showers. Temperature falling to around 38 by 3pm. Breezy, with a northwest wind 18 to 22 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.
Thursday Night
A chance of rain and snow showers before 8pm. Mostly cloudy, then gradually becoming mostly clear, with a low around 33. Breezy, with a west wind 13 to 20 mph. Chance of precipitation is 30%.
Friday
Increasing clouds, with a high near 44. Breezy, with a west wind 6 to 11 mph becoming south 15 to 20 mph in the afternoon.
Friday Night
Mostly cloudy, then gradually becoming mostly clear, with a low around 37. Breezy, with a south wind 20 to 24 mph.
Saturday
Sunny, with a high near 46. Windy.
Saturday Night
Increasing clouds, with a low around 34.
Sunday
Cloudy, with a high near 46.
Sunday Night
Showers, mainly after 2am. Low around 41. Breezy. Chance of precipitation is 80%.
Monday
Showers. High near 53. Breezy. Chance of precipitation is 90%.
Monday Night
Showers likely. Mostly cloudy, with a low around 32. Breezy. Chance of precipitation is 60%.
Tuesday
A 30 percent chance of showers. Partly sunny, with a high near 37.
Tuesday Night
Mostly clear, with a low around 26.
Wednesday
Mostly sunny, with a high near 35.
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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:
7:41 pm EDT Mar 11, 2026
Forecast Valid:
8pm EDT Mar 11, 2026-6pm EDT Mar 18, 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