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.

Overcast

62°F

17°C

Humidity 90%
Wind Speed NE 7 mph
Barometer 30.15 in (1020.8 mb)
Dewpoint 59°F (15°C)
Visibility 10.00 mi
Last update 16 Jun 7:56 am EDT
Extended Forecast for

Port Jefferson NYSimilar City Names

  • Today

    Today: Mostly cloudy, with a high near 68. East wind around 9 mph.

    High: 68 °F

    Mostly Cloudy

  • Tonight

    Tonight: Mostly cloudy, with a low around 61. East wind 5 to 7 mph.

    Low: 61 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 20 percent chance of showers after 2pm. Mostly cloudy, with a high near 71. East wind around 8 mph.

    High: 71 °F

    Cloudy then
    Slight Chance
    Showers

  • Tuesday Night

    Tuesday Night: A 50 percent chance of showers, mainly after 8pm. Cloudy, with a low around 64. South wind 3 to 6 mph.

    Low: 64 °F

    Chance
    Showers

  • Wednesday

    Wednesday: A chance of showers, with thunderstorms also possible after 2pm. Cloudy, then gradually becoming mostly sunny, with a high near 80. Southwest wind 5 to 7 mph. Chance of precipitation is 30%.

    High: 80 °F

    Chance
    Showers

  • Wednesday Night

    Wednesday Night: Partly cloudy, with a low around 69.

    Low: 69 °F

    Partly Cloudy

  • Juneteenth

    Juneteenth: A 30 percent chance of showers and thunderstorms after 2pm. Sunny, with a high near 89.

    High: 89 °F

    Sunny then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: A chance of showers and thunderstorms before 8pm, then a chance of showers between 8pm and 2am. Partly cloudy, with a low around 68. Chance of precipitation is 30%.

    Low: 68 °F

    Chance
    T-storms then
    Chance
    Showers

  • Friday

    Friday: Sunny, with a high near 81.

    High: 81 °F

    Sunny

Detailed Forecast

Today
Mostly cloudy, with a high near 68. East wind around 9 mph.
Tonight
Mostly cloudy, with a low around 61. East wind 5 to 7 mph.
Tuesday
A 20 percent chance of showers after 2pm. Mostly cloudy, with a high near 71. East wind around 8 mph.
Tuesday Night
A 50 percent chance of showers, mainly after 8pm. Cloudy, with a low around 64. South wind 3 to 6 mph.
Wednesday
A chance of showers, with thunderstorms also possible after 2pm. Cloudy, then gradually becoming mostly sunny, with a high near 80. Southwest wind 5 to 7 mph. Chance of precipitation is 30%.
Wednesday Night
Partly cloudy, with a low around 69.
Juneteenth
A 30 percent chance of showers and thunderstorms after 2pm. Sunny, with a high near 89.
Thursday Night
A chance of showers and thunderstorms before 8pm, then a chance of showers between 8pm and 2am. Partly cloudy, with a low around 68. Chance of precipitation is 30%.
Friday
Sunny, with a high near 81.
Friday Night
Partly cloudy, with a low around 64.
Saturday
Sunny, with a high near 80.
Saturday Night
Partly cloudy, with a low around 67.
Sunday
Mostly sunny, with a high near 84.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NYSimilar City Names
 40.95°N 73.05°W (Elev. 151 ft)
Last Update:
6:40 pm EDT Jun 15, 2025
Forecast Valid:
8am EDT Jun 16, 2025-6pm EDT Jun 22, 2025
 
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Additional Resources

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Hourly Weather Forecast

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High Temperature

National Digital Forecast Database Weather Element Forecast

Chance of Precipitation