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 Fog/Mist

49°F

9°C

Humidity 97%
Wind Speed NE 7 mph
Barometer 29.73 in (1006.7 mb)
Dewpoint 48°F (9°C)
Visibility 4.00 mi
Wind Chill46°F (8°C)
Last update 22 Mar 10:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Rain. Low around 38. Calm wind becoming north around 5 mph after midnight. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.

    Low: 38 °F

    Rain

  • Monday

    Monday: Rain, mainly before 11am. High near 45. North wind around 10 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 45 °F

    Rain then
    Partly Sunny

  • Monday Night

    Monday Night: Partly cloudy, with a low around 31. Wind chill values between 25 and 30. Northwest wind 8 to 10 mph.

    Low: 31 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Sunny, with a high near 45. Wind chill values between 25 and 35 early. North wind 6 to 8 mph becoming southwest in the afternoon.

    High: 45 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Increasing clouds, with a low around 34. Southwest wind around 7 mph.

    Low: 34 °F

    Increasing
    Clouds

  • Wednesday

    Wednesday: Partly sunny, with a high near 49.

    High: 49 °F

    Partly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 38.

    Low: 38 °F

    Mostly Cloudy

  • Thursday

    Thursday: Mostly cloudy, with a high near 52.

    High: 52 °F

    Mostly Cloudy

  • Thursday Night

    Thursday Night: Rain likely, mainly after 2am. Mostly cloudy, with a low around 42. Chance of precipitation is 60%.

    Low: 42 °F

    Rain Likely

Detailed Forecast

Tonight
Rain. Low around 38. Calm wind becoming north around 5 mph after midnight. Chance of precipitation is 80%. New precipitation amounts between a quarter and half of an inch possible.
Monday
Rain, mainly before 11am. High near 45. North wind around 10 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Monday Night
Partly cloudy, with a low around 31. Wind chill values between 25 and 30. Northwest wind 8 to 10 mph.
Tuesday
Sunny, with a high near 45. Wind chill values between 25 and 35 early. North wind 6 to 8 mph becoming southwest in the afternoon.
Tuesday Night
Increasing clouds, with a low around 34. Southwest wind around 7 mph.
Wednesday
Partly sunny, with a high near 49.
Wednesday Night
Mostly cloudy, with a low around 38.
Thursday
Mostly cloudy, with a high near 52.
Thursday Night
Rain likely, mainly after 2am. Mostly cloudy, with a low around 42. Chance of precipitation is 60%.
Friday
Rain likely, mainly before 8am. Partly sunny, with a high near 53. Chance of precipitation is 60%.
Friday Night
Partly cloudy, with a low around 26.
Saturday
Sunny, with a high near 41.
Saturday Night
Mostly clear, with a low around 30.
Sunday
Mostly sunny, with a high near 47.
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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:
3:49 pm EDT Mar 22, 2026
Forecast Valid:
11pm EDT Mar 22, 2026-6pm EDT Mar 29, 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