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.

N/A

Humidity NA
Wind Speed NA
Barometer NA
Dewpoint N/A
Visibility NA
Last update *** Not a current observation ***
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: A 30 percent chance of rain. Cloudy, with a steady temperature around 36. Northeast wind around 10 mph.

    Low: 36 °F

    Chance Rain

  • Friday

    Friday: A 30 percent chance of rain before 7am. Patchy fog between 7am and 8am. Otherwise, cloudy, with a high near 40. Northeast wind 7 to 10 mph.

    High: 40 °F

    Chance Rain
    and Patchy
    Fog then
    Cloudy

  • Friday Night

    Friday Night: A chance of drizzle, mainly after 4am. Patchy fog before 8pm, then patchy fog after 9pm. Otherwise, cloudy, with a low around 34. Northeast wind around 6 mph becoming calm after midnight.

    Low: 34 °F

    Chance
    Drizzle and
    Patchy Fog

  • Saturday

    Saturday: A chance of drizzle before 7am. Patchy fog before 10am. Otherwise, cloudy, with a high near 48. Calm wind becoming south 5 to 7 mph in the afternoon.

    High: 48 °F

    Chance
    Drizzle and
    Patchy Fog
    then Cloudy

  • Saturday Night

    Saturday Night: Showers likely, mainly after 1am. Cloudy, with a temperature rising to around 47 by 3am. Southwest wind 6 to 9 mph. Chance of precipitation is 70%.

    Low: 44 °F⇑

    Chance
    Showers then
    Showers
    Likely

  • Sunday

    Sunday: Cloudy, then gradually becoming mostly sunny, with a high near 56.

    High: 56 °F

    Decreasing
    Clouds

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 39.

    Low: 39 °F

    Partly Cloudy

  • Monday

    Monday: Mostly sunny, with a high near 55.

    High: 55 °F

    Mostly Sunny

  • Monday Night

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

    Low: 42 °F

    Partly Cloudy

Detailed Forecast

Overnight
A 30 percent chance of rain. Cloudy, with a steady temperature around 36. Northeast wind around 10 mph.
Friday
A 30 percent chance of rain before 7am. Patchy fog between 7am and 8am. Otherwise, cloudy, with a high near 40. Northeast wind 7 to 10 mph.
Friday Night
A chance of drizzle, mainly after 4am. Patchy fog before 8pm, then patchy fog after 9pm. Otherwise, cloudy, with a low around 34. Northeast wind around 6 mph becoming calm after midnight.
Saturday
A chance of drizzle before 7am. Patchy fog before 10am. Otherwise, cloudy, with a high near 48. Calm wind becoming south 5 to 7 mph in the afternoon.
Saturday Night
Showers likely, mainly after 1am. Cloudy, with a temperature rising to around 47 by 3am. Southwest wind 6 to 9 mph. Chance of precipitation is 70%.
Sunday
Cloudy, then gradually becoming mostly sunny, with a high near 56.
Sunday Night
Partly cloudy, with a low around 39.
Monday
Mostly sunny, with a high near 55.
Monday Night
Partly cloudy, with a low around 42.
Tuesday
Mostly sunny, with a high near 56.
Tuesday Night
Mostly cloudy, with a low around 41.
Wednesday
A 40 percent chance of rain. Mostly cloudy, with a high near 52.
Wednesday Night
Rain likely. Mostly cloudy, with a low around 39. Chance of precipitation is 60%.
Thursday
A 30 percent chance of rain. Partly sunny, with a high near 49.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.93°N 73.06°W (Elev. 161 ft)
Last Update:
1:11 am EST Mar 6, 2026
Forecast Valid:
4am EST Mar 6, 2026-6pm EDT Mar 12, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

Link to Local Radar Data Link to Satellite Data

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