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

77°F

25°C

Humidity 64%
Wind Speed W 10 mph
Barometer 29.85 in (1010.7 mb)
Dewpoint 64°F (18°C)
Visibility 10.00 mi
Heat Index79°F (26°C)
Last update 14 Oct 10:56 am EDT
Extended Forecast for

Holtsville NY

  • Today

    Today: Partly sunny, with a high near 77. West wind 10 to 15 mph.

    High: 77 °F

    Partly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 52. North wind 6 to 9 mph.

    Low: 52 °F

    Partly Cloudy

  • Thursday

    Thursday: Sunny, with a high near 63. North wind 6 to 9 mph.

    High: 63 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers after 2am. Low around 51. Southeast wind 3 to 7 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.

    Low: 51 °F

    Partly Cloudy
    then Showers

  • Friday

    Friday: Showers, with thunderstorms also possible after 5pm. High near 70. Southwest wind 11 to 14 mph, with gusts as high as 25 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

    High: 70 °F

    Showers

  • Friday Night

    Friday Night: Showers likely before 2am. Mostly cloudy, with a low around 43. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

    Low: 43 °F

    Showers
    Likely

  • Saturday

    Saturday: Mostly sunny, with a high near 53. Breezy.

    High: 53 °F

    Mostly Sunny
    and Breezy
    then Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 39.

    Low: 39 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 58.

    High: 58 °F

    Sunny

Detailed Forecast

Today
Partly sunny, with a high near 77. West wind 10 to 15 mph.
Tonight
Partly cloudy, with a low around 52. North wind 6 to 9 mph.
Thursday
Sunny, with a high near 63. North wind 6 to 9 mph.
Thursday Night
Showers after 2am. Low around 51. Southeast wind 3 to 7 mph. Chance of precipitation is 80%. New precipitation amounts of less than a tenth of an inch possible.
Friday
Showers, with thunderstorms also possible after 5pm. High near 70. Southwest wind 11 to 14 mph, with gusts as high as 25 mph. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.
Friday Night
Showers likely before 2am. Mostly cloudy, with a low around 43. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.
Saturday
Mostly sunny, with a high near 53. Breezy.
Saturday Night
Mostly clear, with a low around 39.
Sunday
Sunny, with a high near 58.
Sunday Night
Mostly clear, with a low around 44.
Monday
Sunny, with a high near 62.
Monday Night
Partly cloudy, with a low around 48.
Tuesday
Partly sunny, with a high near 65.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Holtsville NY
 40.82°N 73.05°W (Elev. 112 ft)
Last Update:
10:46 am EDT Oct 14, 2026
Forecast Valid:
11am EDT Oct 14, 2026-6pm EDT Oct 20, 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