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.

Mostly Cloudy

78°F

26°C

Humidity 82%
Wind Speed W 5 mph
Barometer 30.01 in (1016.2 mb)
Dewpoint 72°F (22°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 28 Aug 10:56 am EDT
Extended Forecast for

Holtsville NY

  • Today

    Today: A slight chance of showers, then a chance of showers and thunderstorms after 2pm. Mostly cloudy, with a high near 81. Southwest wind around 6 mph. Chance of precipitation is 40%.

    High: 81 °F

    Chance
    T-storms

  • Tonight

    Tonight: A 30 percent chance of showers and thunderstorms before 8pm. Mostly cloudy, with a low around 63. Calm wind becoming north 5 to 7 mph after midnight.

    Low: 63 °F

    Chance
    T-storms then
    Mostly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 78. North wind 3 to 8 mph.

    High: 78 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 62. Light south wind.

    Low: 62 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 80. Light west wind becoming southwest 5 to 10 mph in the morning.

    High: 80 °F

    Sunny

  • Sunday Night

    Sunday Night: Partly cloudy, with a low around 68.

    Low: 68 °F

    Partly Cloudy

  • Monday

    Monday: Partly sunny, with a high near 82.

    High: 82 °F

    Partly Sunny

  • Monday Night

    Monday Night: Mostly cloudy, with a low around 67.

    Low: 67 °F

    Mostly Cloudy

  • Tuesday

    Tuesday: A 40 percent chance of showers after 8am. Mostly cloudy, with a high near 79.

    High: 79 °F

    Chance
    Showers

Detailed Forecast

Today
A slight chance of showers, then a chance of showers and thunderstorms after 2pm. Mostly cloudy, with a high near 81. Southwest wind around 6 mph. Chance of precipitation is 40%.
Tonight
A 30 percent chance of showers and thunderstorms before 8pm. Mostly cloudy, with a low around 63. Calm wind becoming north 5 to 7 mph after midnight.
Saturday
Mostly sunny, with a high near 78. North wind 3 to 8 mph.
Saturday Night
Mostly clear, with a low around 62. Light south wind.
Sunday
Sunny, with a high near 80. Light west wind becoming southwest 5 to 10 mph in the morning.
Sunday Night
Partly cloudy, with a low around 68.
Monday
Partly sunny, with a high near 82.
Monday Night
Mostly cloudy, with a low around 67.
Tuesday
A 40 percent chance of showers after 8am. Mostly cloudy, with a high near 79.
Tuesday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 68.
Wednesday
A 50 percent chance of showers. Mostly cloudy, with a high near 80.
Wednesday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 67.
Thursday
Partly sunny, with a high near 81.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Holtsville NY
 40.82°N 73.05°W (Elev. 112 ft)
Last Update:
4:20 am EDT Aug 28, 2026
Forecast Valid:
11am EDT Aug 28, 2026-6pm EDT Sep 3, 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