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.

Fair

86°F

30°C

Humidity 59%
Wind Speed SW 12 mph
Barometer 29.92 in (1013.1 mb)
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Heat Index91°F (33°C)
Last update 2 Jul 6:56 pm EDT
Extended Forecast for

Holtsville NY

Extreme Heat Warning July 2, 07:02pm until July 4, 09:00pm
Click here for hazard details and duration
Extreme Heat Warning
  •  
    Extreme Heat Warning July 2, 07:02pm until July 4, 09:00pm

    NOW until 9:00pm Sat

    Extreme Heat Warning

  • Tonight

    Low: 77 °F

    Clear

  • Friday

    Friday: Sunny, with a high near 98. Heat index values as high as 107. Light and variable wind becoming west 5 to 8 mph in the morning.

    High: 98 °F

    Sunny

  • Friday Night

    Friday Night: A slight chance of showers and thunderstorms before 11pm, then a slight chance of showers between 11pm and 2am. Mostly clear, with a low around 77. Southwest wind 3 to 6 mph. Chance of precipitation is 20%.

    Low: 77 °F

    Slight Chance
    T-storms then
    Slight Chance
    Showers

  • Independence Day

    Independence Day: Showers likely and possibly a thunderstorm after 2pm. Increasing clouds, with a high near 93. Heat index values as high as 102. West wind 5 to 10 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 93 °F

    Mostly Sunny
    then Showers
    Likely

  • Saturday Night

    Saturday Night: Showers likely and possibly a thunderstorm before 8pm, then a chance of showers between 8pm and 2am. Mostly cloudy, with a low around 74. West wind around 6 mph becoming light and variable after midnight. Chance of precipitation is 60%.

    Low: 74 °F

    Showers
    Likely

  • Sunday

    Sunday: Mostly sunny, with a high near 86.

    High: 86 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: A 50 percent chance of showers after 8pm. Mostly cloudy, with a low around 69.

    Low: 69 °F

    Chance
    Showers

  • Monday

    Monday: A 50 percent chance of showers. Mostly cloudy, with a high near 81.

    High: 81 °F

    Chance
    Showers

Detailed Forecast

Tonight
Clear, with a low around 77. Southwest wind 5 to 9 mph becoming light and variable after midnight.
Friday
Sunny, with a high near 98. Heat index values as high as 107. Light and variable wind becoming west 5 to 8 mph in the morning.
Friday Night
A slight chance of showers and thunderstorms before 11pm, then a slight chance of showers between 11pm and 2am. Mostly clear, with a low around 77. Southwest wind 3 to 6 mph. Chance of precipitation is 20%.
Independence Day
Showers likely and possibly a thunderstorm after 2pm. Increasing clouds, with a high near 93. Heat index values as high as 102. West wind 5 to 10 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Saturday Night
Showers likely and possibly a thunderstorm before 8pm, then a chance of showers between 8pm and 2am. Mostly cloudy, with a low around 74. West wind around 6 mph becoming light and variable after midnight. Chance of precipitation is 60%.
Sunday
Mostly sunny, with a high near 86.
Sunday Night
A 50 percent chance of showers after 8pm. Mostly cloudy, with a low around 69.
Monday
A 50 percent chance of showers. Mostly cloudy, with a high near 81.
Monday Night
Showers likely, mainly after 2am. Mostly cloudy, with a low around 67. Chance of precipitation is 60%.
Tuesday
Showers likely, mainly before 8am. Partly sunny, with a high near 81. Chance of precipitation is 60%.
Tuesday Night
Partly cloudy, with a low around 67.
Wednesday
Mostly sunny, with a high near 83.
Wednesday Night
Partly cloudy, with a low around 68.
Thursday
Mostly sunny, with a high near 86.
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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:
2:25 pm EDT Jul 2, 2026
Forecast Valid:
7pm EDT Jul 2, 2026-6pm EDT Jul 9, 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