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.

Fair

30°F

-1°C

Humidity 56%
Wind Speed N 10 mph
Barometer 30.51 in (1033.1 mb)
Dewpoint 16°F (-9°C)
Visibility 10.00 mi
Wind Chill21°F (-6°C)
Last update 8 Apr 3:56 am EDT
Extended Forecast for

Port Jefferson NY

  • Today

    Today: Sunny, with a high near 47. Wind chill values between 25 and 35 early. North wind 8 to 13 mph becoming southeast in the afternoon.

    High: 47 °F

    Sunny

  • Tonight

    Tonight: Patchy frost after midnight. Otherwise, clear, with a low around 33. South wind 3 to 8 mph.

    Low: 33 °F

    Clear then
    Patchy Frost

  • Thursday

    Thursday: Patchy frost before 9am. Otherwise, sunny, with a high near 53. Southeast wind 6 to 8 mph.

    High: 53 °F

    Patchy Frost
    then Sunny

  • Thursday Night

    Thursday Night: Patchy frost after 4am. Otherwise, mostly clear, with a low around 38. South wind 5 to 7 mph becoming calm after midnight.

    Low: 38 °F

    Mostly Clear
    then Patchy
    Frost

  • Friday

    Friday: Patchy frost before 7am. Otherwise, sunny, with a high near 58. Calm wind becoming south 5 to 8 mph in the afternoon.

    High: 58 °F

    Patchy Frost
    then Sunny

  • Friday Night

    Friday Night: Mostly cloudy, with a low around 45.

    Low: 45 °F

    Mostly Cloudy

  • Saturday

    Saturday: Partly sunny, then gradually becoming sunny, with a high near 59.

    High: 59 °F

    Becoming
    Sunny

  • Saturday Night

    Saturday Night: Clear, with a low around 41.

    Low: 41 °F

    Clear

  • Sunday

    Sunday: Sunny, with a high near 56.

    High: 56 °F

    Sunny

Detailed Forecast

Today
Sunny, with a high near 47. Wind chill values between 25 and 35 early. North wind 8 to 13 mph becoming southeast in the afternoon.
Tonight
Patchy frost after midnight. Otherwise, clear, with a low around 33. South wind 3 to 8 mph.
Thursday
Patchy frost before 9am. Otherwise, sunny, with a high near 53. Southeast wind 6 to 8 mph.
Thursday Night
Patchy frost after 4am. Otherwise, mostly clear, with a low around 38. South wind 5 to 7 mph becoming calm after midnight.
Friday
Patchy frost before 7am. Otherwise, sunny, with a high near 58. Calm wind becoming south 5 to 8 mph in the afternoon.
Friday Night
Mostly cloudy, with a low around 45.
Saturday
Partly sunny, then gradually becoming sunny, with a high near 59.
Saturday Night
Clear, with a low around 41.
Sunday
Sunny, with a high near 56.
Sunday Night
Mostly cloudy, with a low around 46.
Monday
Partly sunny, with a high near 64.
Monday Night
Mostly cloudy, with a low around 54.
Tuesday
Partly sunny, with a high near 70.
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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:
3:28 am EDT Apr 8, 2026
Forecast Valid:
4am EDT Apr 8, 2026-6pm EDT Apr 14, 2026
 
Forecast Discussion
 
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Additional Resources

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Chance of Precipitation