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

73°F

23°C

Humidity 71%
Wind Speed W 9 mph
Barometer 29.89 in (1012.2 mb)
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Last update 14 Oct 8:56 pm EDT
Extended Forecast for

Mount Sinai NY

  • Tonight

    Tonight: Mostly clear, with a low around 52. North wind around 9 mph.

    Low: 52 °F

    Mostly Clear

  • Thursday

    Thursday: Sunny, with a high near 60. North wind 6 to 9 mph.

    High: 60 °F

    Sunny

  • Thursday Night

    Thursday Night: Showers likely, mainly after 5am. Increasing clouds, with a low around 51. Southeast wind 5 to 7 mph. Chance of precipitation is 60%.

    Low: 51 °F

    Mostly Clear
    then Showers
    Likely

  • Friday

    Friday: Showers, with thunderstorms also possible after 5pm. High near 70. Southwest wind 10 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    High: 70 °F

    Showers

  • Friday Night

    Friday Night: Showers and thunderstorms. Low around 46. Southwest wind 11 to 16 mph becoming northwest after midnight. Winds could gust as high as 29 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

    Low: 46 °F

    Showers

  • Saturday

    Saturday: A 30 percent chance of showers before 8am. Partly sunny, with a high near 53. Breezy.

    High: 53 °F

    Breezy.
    Chance
    Showers then
    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly clear, with a low around 40.

    Low: 40 °F

    Mostly Clear

  • Sunday

    Sunday: Sunny, with a high near 55.

    High: 55 °F

    Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 45.

    Low: 45 °F

    Mostly Clear

Detailed Forecast

Tonight
Mostly clear, with a low around 52. North wind around 9 mph.
Thursday
Sunny, with a high near 60. North wind 6 to 9 mph.
Thursday Night
Showers likely, mainly after 5am. Increasing clouds, with a low around 51. Southeast wind 5 to 7 mph. Chance of precipitation is 60%.
Friday
Showers, with thunderstorms also possible after 5pm. High near 70. Southwest wind 10 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Friday Night
Showers and thunderstorms. Low around 46. Southwest wind 11 to 16 mph becoming northwest after midnight. Winds could gust as high as 29 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Saturday
A 30 percent chance of showers before 8am. Partly sunny, with a high near 53. Breezy.
Saturday Night
Mostly clear, with a low around 40.
Sunday
Sunny, with a high near 55.
Sunday Night
Mostly clear, with a low around 45.
Monday
Sunny, with a high near 60.
Monday Night
Partly cloudy, with a low around 48.
Tuesday
Mostly sunny, with a high near 63.
Tuesday Night
Partly cloudy, with a low around 48.
Wednesday
Sunny, with a high near 62.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Mount Sinai NY
 40.93°N 73.03°W (Elev. 151 ft)
Last Update:
7:37 pm EDT Oct 14, 2026
Forecast Valid:
10pm EDT Oct 14, 2026-6pm EDT Oct 21, 2026
 
Forecast Discussion
 
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Additional Resources

Radar & Satellite Image

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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