National Oceanic and Atmospheric Administration National Weather Service United States Department of Commerce

Hazardous Weather Conditions

Current conditions at

Islip, Long Island Mac Arthur Airport (KISP)

Lat: 40.79°NLon: 73.1°WElev: 98ft.

Mostly Cloudy

80°F

27°C

Humidity 37%
Wind Speed NW 16 G 25 mph
Barometer 29.74 in (1007.0 mb)
Dewpoint 51°F (11°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 20 Jun 1:56 pm EDT
Extended Forecast for

Port Jefferson NY

  • Tonight

    Tonight: Mostly clear, with a low around 65. Northwest wind 8 to 13 mph becoming light west after midnight. Winds could gust as high as 24 mph.

    Low: 65 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 81. West wind 3 to 6 mph.

    High: 81 °F

    Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 65. West wind around 5 mph becoming calm in the evening.

    Low: 65 °F

    Partly Cloudy

  • Monday

    Monday: A chance of showers, then showers and possibly a thunderstorm after 2pm. High near 76. Light east wind increasing to 6 to 11 mph in the morning. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.

    High: 76 °F

    Chance
    Showers then
    Showers

  • Monday Night

    Monday Night: Showers and possibly a thunderstorm. Low around 67. South wind 11 to 14 mph. Chance of precipitation is 100%. New rainfall amounts between three quarters and one inch possible.

    Low: 67 °F

    Showers

  • Tuesday

    Tuesday: Showers likely, mainly before 2pm. Mostly cloudy, with a high near 80. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 80 °F

    Showers
    Likely

  • Tuesday Night

    Tuesday Night: A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 66.

    Low: 66 °F

    Chance
    Showers then
    Partly Cloudy

  • Wednesday

    Wednesday: Sunny, with a high near 82.

    High: 82 °F

    Sunny

  • Wednesday Night

    Wednesday Night: Mostly clear, with a low around 67.

    Low: 67 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly clear, with a low around 65. Northwest wind 8 to 13 mph becoming light west after midnight. Winds could gust as high as 24 mph.
Sunday
Sunny, with a high near 81. West wind 3 to 6 mph.
Sunday Night
Partly cloudy, with a low around 65. West wind around 5 mph becoming calm in the evening.
Monday
A chance of showers, then showers and possibly a thunderstorm after 2pm. High near 76. Light east wind increasing to 6 to 11 mph in the morning. Chance of precipitation is 80%. New rainfall amounts between a half and three quarters of an inch possible.
Monday Night
Showers and possibly a thunderstorm. Low around 67. South wind 11 to 14 mph. Chance of precipitation is 100%. New rainfall amounts between three quarters and one inch possible.
Tuesday
Showers likely, mainly before 2pm. Mostly cloudy, with a high near 80. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.
Tuesday Night
A 30 percent chance of showers before 8pm. Partly cloudy, with a low around 66.
Wednesday
Sunny, with a high near 82.
Wednesday Night
Mostly clear, with a low around 67.
Thursday
Sunny, with a high near 82.
Thursday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 67.
Friday
A 40 percent chance of showers. Partly sunny, with a high near 82.
Friday Night
Partly cloudy, with a low around 69.
Saturday
Mostly sunny, with a high near 85.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
2:28 pm EDT Jun 20, 2026
Forecast Valid:
3pm EDT Jun 20, 2026-6pm EDT Jun 27, 2026
 
Forecast Discussion
 
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Additional Resources

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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