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

79°F

26°C

Humidity 49%
Wind Speed N 7 mph
Barometer 30.04 in (1017.1 mb)
Dewpoint 58°F (14°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 14 Aug 9:56 am EDT
Extended Forecast for

Holtsville NY

  • Today

    Today: Mostly sunny, with a high near 84. North wind 6 to 9 mph becoming southwest in the afternoon.

    High: 84 °F

    Mostly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 65. Calm wind becoming north around 6 mph after midnight.

    Low: 65 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 81. Northeast wind 7 to 9 mph.

    High: 81 °F

    Sunny

  • Saturday Night

    Saturday Night: Partly cloudy, with a low around 63. South wind around 6 mph becoming calm in the evening.

    Low: 63 °F

    Partly Cloudy

  • Sunday

    Sunday: A 30 percent chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 81. South wind 5 to 13 mph.

    High: 81 °F

    Mostly Sunny
    then Chance
    Showers

  • Sunday Night

    Sunday Night: Showers, mainly after 8pm. Low around 70. Chance of precipitation is 90%. New precipitation amounts between a half and three quarters of an inch possible.

    Low: 70 °F

    Showers

  • Monday

    Monday: A 40 percent chance of showers before 2pm. Cloudy, then gradually becoming mostly sunny, with a high near 85.

    High: 85 °F

    Chance
    Showers

  • Monday Night

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

    Low: 67 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Sunny, with a high near 83.

    High: 83 °F

    Sunny

Detailed Forecast

Today
Mostly sunny, with a high near 84. North wind 6 to 9 mph becoming southwest in the afternoon.
Tonight
Partly cloudy, with a low around 65. Calm wind becoming north around 6 mph after midnight.
Saturday
Sunny, with a high near 81. Northeast wind 7 to 9 mph.
Saturday Night
Partly cloudy, with a low around 63. South wind around 6 mph becoming calm in the evening.
Sunday
A 30 percent chance of showers and thunderstorms after 2pm. Partly sunny, with a high near 81. South wind 5 to 13 mph.
Sunday Night
Showers, mainly after 8pm. Low around 70. Chance of precipitation is 90%. New precipitation amounts between a half and three quarters of an inch possible.
Monday
A 40 percent chance of showers before 2pm. Cloudy, then gradually becoming mostly sunny, with a high near 85.
Monday Night
Partly cloudy, with a low around 67.
Tuesday
Sunny, with a high near 83.
Tuesday Night
Mostly clear, with a low around 67.
Wednesday
Sunny, with a high near 83.
Wednesday Night
Partly cloudy, with a low around 70.
Thursday
A 40 percent chance of showers. Mostly sunny, with a high near 84.
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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:
3:11 am EDT Aug 14, 2026
Forecast Valid:
9am EDT Aug 14, 2026-6pm EDT Aug 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