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

38°F

3°C

Humidity 46%
Wind Speed S 15 G 22 mph
Barometer 30.01 in (1016.2 mb)
Dewpoint 19°F (-7°C)
Visibility 10.00 mi
Wind Chill29°F (-2°C)
Last update 13 Mar 2:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: A slight chance of showers between 11pm and 2am. Mostly cloudy, then gradually becoming mostly clear, with a low around 37. South wind 13 to 18 mph, with gusts as high as 29 mph. Chance of precipitation is 20%.

    Low: 37 °F

    Slight Chance
    Showers

  • Saturday

    Saturday: Sunny, with a high near 47. Breezy, with a west wind 17 to 21 mph, with gusts as high as 37 mph.

    High: 47 °F

    Sunny and
    Breezy

  • Saturday Night

    Saturday Night: Increasing clouds, with a low around 32. Northwest wind 8 to 13 mph becoming light after midnight.

    Low: 32 °F

    Increasing
    Clouds

  • Sunday

    Sunday: Mostly cloudy, with a high near 47. Light and variable wind becoming southeast 5 to 9 mph in the morning.

    High: 47 °F

    Mostly Cloudy

  • Sunday Night

    Sunday Night: Rain after 2am. Low around 39. Southeast wind 10 to 16 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 39 °F

    Mostly Cloudy
    then Rain

  • Monday

    Monday: Rain, with thunderstorms also possible after 2pm. High near 57. Chance of precipitation is 100%. New rainfall amounts between a half and three quarters of an inch possible.

    High: 57 °F

    Rain

  • Monday Night

    Monday Night: Rain and possibly a thunderstorm. Low around 36. Breezy. Chance of precipitation is 100%.

    Low: 36 °F

    Rain and
    Breezy

  • Tuesday

    Tuesday: A 30 percent chance of rain before 8am. Mostly sunny, with a high near 44.

    High: 44 °F

    Chance Rain
    then Mostly
    Sunny

  • Tuesday Night

    Tuesday Night: Partly cloudy, with a low around 24.

    Low: 24 °F

    Partly Cloudy

Detailed Forecast

Tonight
A slight chance of showers between 11pm and 2am. Mostly cloudy, then gradually becoming mostly clear, with a low around 37. South wind 13 to 18 mph, with gusts as high as 29 mph. Chance of precipitation is 20%.
Saturday
Sunny, with a high near 47. Breezy, with a west wind 17 to 21 mph, with gusts as high as 37 mph.
Saturday Night
Increasing clouds, with a low around 32. Northwest wind 8 to 13 mph becoming light after midnight.
Sunday
Mostly cloudy, with a high near 47. Light and variable wind becoming southeast 5 to 9 mph in the morning.
Sunday Night
Rain after 2am. Low around 39. Southeast wind 10 to 16 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Monday
Rain, with thunderstorms also possible after 2pm. High near 57. Chance of precipitation is 100%. New rainfall amounts between a half and three quarters of an inch possible.
Monday Night
Rain and possibly a thunderstorm. Low around 36. Breezy. Chance of precipitation is 100%.
Tuesday
A 30 percent chance of rain before 8am. Mostly sunny, with a high near 44.
Tuesday Night
Partly cloudy, with a low around 24.
Wednesday
Mostly sunny, with a high near 38.
Wednesday Night
Mostly cloudy, with a low around 30.
Thursday
Partly sunny, with a high near 43.
Thursday Night
Partly cloudy, with a low around 33.
Friday
Mostly sunny, with a high near 46.
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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:
2:26 pm EDT Mar 13, 2026
Forecast Valid:
3pm EDT Mar 13, 2026-6pm EDT Mar 20, 2026
 
Forecast Discussion
 
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Additional Resources

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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