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.

Fair

45°F

7°C

Humidity 26%
Wind Speed Vrbl 5 mph
Barometer 30.33 in (1027.2 mb)
Dewpoint 12°F (-11°C)
Visibility 10.00 mi
Wind Chill42°F (6°C)
Last update 24 Mar 2:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Increasing clouds, with a low around 31. Wind chill values between 20 and 25. South wind 8 to 11 mph.

    Low: 31 °F

    Increasing
    Clouds

  • Wednesday

    Wednesday: Partly sunny, with a high near 50. Wind chill values between 25 and 35 early. West wind 5 to 8 mph.

    High: 50 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Cloudy, with a low around 39. South wind around 11 mph.

    Low: 39 °F

    Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 58. Southwest wind 13 to 16 mph.

    High: 58 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Rain, mainly after 2am. Low around 46. Breezy, with a south wind 17 to 20 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 46 °F

    Breezy.
    Slight Chance
    Rain then
    Rain

  • Friday

    Friday: Rain likely, mainly before 8am. Mostly cloudy, with a temperature falling to around 46 by 2pm. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.

    High: 52 °F⇓

    Rain Likely
    then Mostly
    Cloudy

  • Friday Night

    Friday Night: Partly cloudy, with a low around 30.

    Low: 30 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 41.

    High: 41 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 34.

    Low: 34 °F

    Partly Cloudy

Detailed Forecast

Tonight
Increasing clouds, with a low around 31. Wind chill values between 20 and 25. South wind 8 to 11 mph.
Wednesday
Partly sunny, with a high near 50. Wind chill values between 25 and 35 early. West wind 5 to 8 mph.
Wednesday Night
Cloudy, with a low around 39. South wind around 11 mph.
Thursday
Mostly cloudy, with a high near 58. Southwest wind 13 to 16 mph.
Thursday Night
Rain, mainly after 2am. Low around 46. Breezy, with a south wind 17 to 20 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday
Rain likely, mainly before 8am. Mostly cloudy, with a temperature falling to around 46 by 2pm. Chance of precipitation is 60%. New precipitation amounts of less than a tenth of an inch possible.
Friday Night
Partly cloudy, with a low around 30.
Saturday
Sunny, with a high near 41.
Saturday Night
Partly cloudy, with a low around 34.
Sunday
Sunny, with a high near 46.
Sunday Night
Partly cloudy, with a low around 38.
Monday
Partly sunny, with a high near 51.
Monday Night
Partly cloudy, with a low around 41.
Tuesday
Partly sunny, with a high near 51.
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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:
2:08 pm EDT Mar 24, 2026
Forecast Valid:
3pm EDT Mar 24, 2026-6pm EDT Mar 31, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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