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 Rain

43°F

6°C

Humidity 86%
Wind Speed SW 12 G 23 mph
Barometer 29.86 in (1011.0 mb)
Dewpoint 39°F (4°C)
Visibility 8.00 mi
Wind Chill37°F (3°C)
Last update 20 Mar 8:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Showers, mainly before 2am. Patchy fog after 2am. Low around 43. Southwest wind 8 to 15 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 43 °F

    Showers then
    Showers
    Likely and
    Patchy Fog

  • Saturday

    Saturday: Patchy fog before 7am. Otherwise, mostly cloudy, then gradually becoming sunny, with a high near 53. Northwest wind 7 to 11 mph.

    High: 53 °F

    Patchy Fog
    then Mostly
    Sunny

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 39. Light and variable wind.

    Low: 39 °F

    Increasing
    Clouds

  • Sunday

    Sunday: A 20 percent chance of rain after 2pm. Mostly cloudy, with a high near 55. South wind 6 to 10 mph.

    High: 55 °F

    Mostly Cloudy
    then Slight
    Chance Rain

  • Sunday Night

    Sunday Night: Rain likely, mainly after 8pm. Cloudy, with a low around 39. South wind around 7 mph becoming north after midnight. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 39 °F

    Rain Likely

  • Monday

    Monday: A 40 percent chance of rain before 2pm. Mostly cloudy, with a high near 47.

    High: 47 °F

    Chance Rain

  • Monday Night

    Monday Night: Partly cloudy, with a low around 31.

    Low: 31 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Sunny, with a high near 44.

    High: 44 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 35.

    Low: 35 °F

    Mostly Cloudy

Detailed Forecast

Tonight
Showers, mainly before 2am. Patchy fog after 2am. Low around 43. Southwest wind 8 to 15 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday
Patchy fog before 7am. Otherwise, mostly cloudy, then gradually becoming sunny, with a high near 53. Northwest wind 7 to 11 mph.
Saturday Night
Increasing clouds, with a low around 39. Light and variable wind.
Sunday
A 20 percent chance of rain after 2pm. Mostly cloudy, with a high near 55. South wind 6 to 10 mph.
Sunday Night
Rain likely, mainly after 8pm. Cloudy, with a low around 39. South wind around 7 mph becoming north after midnight. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.
Monday
A 40 percent chance of rain before 2pm. Mostly cloudy, with a high near 47.
Monday Night
Partly cloudy, with a low around 31.
Tuesday
Sunny, with a high near 44.
Tuesday Night
Mostly cloudy, with a low around 35.
Wednesday
Partly sunny, with a high near 47.
Wednesday Night
Partly cloudy, with a low around 32.
Thursday
Mostly sunny, with a high near 51.
Thursday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 37.
Friday
A 40 percent chance of rain. 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
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
8:14 pm EDT Mar 20, 2026
Forecast Valid:
9pm EDT Mar 20, 2026-6pm EDT Mar 27, 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