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.

Rain Fog/Mist

39°F

4°C

Humidity 96%
Wind Speed E 7 mph
Barometer 30.25 in (1024.3 mb)
Dewpoint 38°F (3°C)
Visibility 1.50 mi
Wind Chill34°F (1°C)
Last update 5 Mar 10:56 am EST
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Rain. Patchy fog. High near 38. East wind 7 to 11 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 38 °F

    Rain and
    Patchy Fog

  • Tonight

    Tonight: Rain, mainly before 4am. Patchy fog. Low around 36. Northeast wind 16 to 18 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.

    Low: 36 °F

    Rain and
    Patchy Fog

  • Friday

    Friday: A 30 percent chance of rain, mainly before 7am. Patchy fog before 10am. Otherwise, cloudy, with a high near 40. Northeast wind 10 to 17 mph.

    High: 40 °F

    Chance Rain
    and Patchy
    Fog

  • Friday Night

    Friday Night: A 20 percent chance of rain after 1am. Cloudy, with a low around 36. Northeast wind 5 to 9 mph becoming light east after midnight.

    Low: 36 °F

    Cloudy then
    Slight Chance
    Rain

  • Saturday

    Saturday: Cloudy, with a high near 47. Light southeast wind becoming south 5 to 10 mph in the morning.

    High: 47 °F

    Cloudy

  • Saturday Night

    Saturday Night: Showers likely. Cloudy, with a temperature rising to around 47 by 4am. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 44 °F⇑

    Showers
    Likely

  • Sunday

    Sunday: Partly sunny, with a high near 52.

    High: 52 °F

    Partly Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 42.

    Low: 42 °F

    Partly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 52.

    High: 52 °F

    Mostly Sunny

Detailed Forecast

Today
Rain. Patchy fog. High near 38. East wind 7 to 11 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.
Tonight
Rain, mainly before 4am. Patchy fog. Low around 36. Northeast wind 16 to 18 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.
Friday
A 30 percent chance of rain, mainly before 7am. Patchy fog before 10am. Otherwise, cloudy, with a high near 40. Northeast wind 10 to 17 mph.
Friday Night
A 20 percent chance of rain after 1am. Cloudy, with a low around 36. Northeast wind 5 to 9 mph becoming light east after midnight.
Saturday
Cloudy, with a high near 47. Light southeast wind becoming south 5 to 10 mph in the morning.
Saturday Night
Showers likely. Cloudy, with a temperature rising to around 47 by 4am. Chance of precipitation is 70%. New precipitation amounts of less than a tenth of an inch possible.
Sunday
Partly sunny, with a high near 52.
Sunday Night
Partly cloudy, with a low around 42.
Monday
Mostly sunny, with a high near 52.
Monday Night
Partly cloudy, with a low around 45.
Tuesday
Mostly sunny, with a high near 56.
Tuesday Night
Mostly cloudy, with a low around 45.
Wednesday
A 30 percent chance of rain. Mostly cloudy, with a high near 53. Breezy.
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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:
6:25 am EST Mar 5, 2026
Forecast Valid:
11am EST Mar 5, 2026-6pm EDT Mar 11, 2026
 
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Additional Resources

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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