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.

A Few Clouds

80°F

27°C

Humidity 47%
Wind Speed SW 12 mph
Barometer 29.93 in (1013.3 mb)
Dewpoint 58°F (14°C)
Visibility 10.00 mi
Heat Index81°F (27°C)
Last update 24 Aug 2:56 pm EDT
Extended Forecast for

Holtsville NY

  • This Afternoon

    This Afternoon: A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 80. Southwest wind around 14 mph.

    High: 80 °F

    Slight Chance
    T-storms

  • Tonight

    Tonight: Mostly clear, with a low around 62. West wind 3 to 5 mph.

    Low: 62 °F

    Mostly Clear

  • Tuesday

    Tuesday: Sunny, with a high near 78. West wind 8 to 11 mph, with gusts as high as 21 mph.

    High: 78 °F

    Sunny

  • Tuesday Night

    Tuesday Night: Patchy fog after 3am. Otherwise, mostly clear, with a low around 62. West wind 5 to 7 mph becoming northwest after midnight.

    Low: 62 °F

    Partly Cloudy
    then Patchy
    Fog

  • Wednesday

    Wednesday: Patchy fog before 7am. Otherwise, sunny, with a high near 78. Northwest wind around 9 mph becoming west in the afternoon.

    High: 78 °F

    Patchy Fog
    then Mostly
    Sunny

  • Wednesday Night

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

    Low: 68 °F

    Partly Cloudy

  • Thursday

    Thursday: A chance of showers, with thunderstorms also possible after 2pm. Partly sunny, with a high near 79. Chance of precipitation is 40%.

    High: 79 °F

    Chance
    Showers then
    Chance
    T-storms

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 68. Chance of precipitation is 70%.

    Low: 68 °F

    Showers
    Likely

  • Friday

    Friday: Partly sunny, with a high near 81.

    High: 81 °F

    Partly Sunny

Detailed Forecast

This Afternoon
A 20 percent chance of showers and thunderstorms. Mostly sunny, with a high near 80. Southwest wind around 14 mph.
Tonight
Mostly clear, with a low around 62. West wind 3 to 5 mph.
Tuesday
Sunny, with a high near 78. West wind 8 to 11 mph, with gusts as high as 21 mph.
Tuesday Night
Patchy fog after 3am. Otherwise, mostly clear, with a low around 62. West wind 5 to 7 mph becoming northwest after midnight.
Wednesday
Patchy fog before 7am. Otherwise, sunny, with a high near 78. Northwest wind around 9 mph becoming west in the afternoon.
Wednesday Night
Partly cloudy, with a low around 68.
Thursday
A chance of showers, with thunderstorms also possible after 2pm. Partly sunny, with a high near 79. Chance of precipitation is 40%.
Thursday Night
Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 68. Chance of precipitation is 70%.
Friday
Partly sunny, with a high near 81.
Friday Night
Mostly cloudy, with a low around 66.
Saturday
Mostly sunny, with a high near 79.
Saturday Night
Partly cloudy, with a low around 64.
Sunday
Mostly sunny, with a high near 78.
Sunday Night
Partly cloudy, with a low around 67.
Monday
Mostly 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:
2:49 pm EDT Aug 24, 2026
Forecast Valid:
3pm EDT Aug 24, 2026-6pm EDT Aug 31, 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