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.

A Few Clouds

50°F

10°C

Humidity 77%
Wind Speed SW 9 mph
Barometer 29.89 in (1012.1 mb)
Dewpoint 43°F (6°C)
Visibility 10.00 mi
Wind Chill46°F (8°C)
Last update 2 May 12:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Overnight

    Overnight: A 30 percent chance of rain, mainly after 5am. Mostly cloudy, with a low around 48. South wind around 7 mph.

    Low: 48 °F

    Chance Rain

  • Saturday

    Saturday: A 30 percent chance of rain before 11am. Cloudy, with a high near 59. Southwest wind 8 to 10 mph becoming northwest in the afternoon.

    High: 59 °F

    Chance Rain
    then Cloudy

  • Saturday Night

    Saturday Night: A 40 percent chance of rain. Mostly cloudy, with a low around 43. North wind 5 to 9 mph.

    Low: 43 °F

    Chance Rain

  • Sunday

    Sunday: Mostly sunny, with a high near 61. Northwest wind 11 to 13 mph.

    High: 61 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 46. Southwest wind 5 to 9 mph.

    Low: 46 °F

    Mostly Clear

  • Monday

    Monday: Sunny, with a high near 65.

    High: 65 °F

    Sunny

  • Monday Night

    Monday Night: Mostly clear, with a low around 52.

    Low: 52 °F

    Mostly Clear

  • Tuesday

    Tuesday: Mostly sunny, with a high near 69.

    High: 69 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly cloudy, with a low around 54.

    Low: 54 °F

    Mostly Cloudy

Detailed Forecast

Overnight
A 30 percent chance of rain, mainly after 5am. Mostly cloudy, with a low around 48. South wind around 7 mph.
Saturday
A 30 percent chance of rain before 11am. Cloudy, with a high near 59. Southwest wind 8 to 10 mph becoming northwest in the afternoon.
Saturday Night
A 40 percent chance of rain. Mostly cloudy, with a low around 43. North wind 5 to 9 mph.
Sunday
Mostly sunny, with a high near 61. Northwest wind 11 to 13 mph.
Sunday Night
Mostly clear, with a low around 46. Southwest wind 5 to 9 mph.
Monday
Sunny, with a high near 65.
Monday Night
Mostly clear, with a low around 52.
Tuesday
Mostly sunny, with a high near 69.
Tuesday Night
Mostly cloudy, with a low around 54.
Wednesday
A 50 percent chance of showers. Mostly cloudy, with a high near 65.
Wednesday Night
Showers likely. Mostly cloudy, with a low around 51. Chance of precipitation is 70%.
Thursday
Showers likely. Mostly cloudy, with a high near 63. Chance of precipitation is 70%.
Thursday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 46.
Friday
Mostly sunny, with a high near 62.
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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:
10:18 pm EDT May 1, 2026
Forecast Valid:
1am EDT May 2, 2026-6pm EDT May 8, 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