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

77°F

25°C

Humidity 94%
Wind Speed Calm
Barometer 30.05 in (1017.3 mb)
Dewpoint 75°F (24°C)
Visibility 9.00 mi
Heat Index78°F (26°C)
Last update 16 Jul 2:56 am EDT
Extended Forecast for

Mount Sinai NY

Heat Advisory July 16, 11:00am until July 17, 10:00pm
Click here for hazard details and duration
Heat Advisory

  • Overnight

    Overnight: Patchy fog after 5am. Otherwise, partly cloudy, with a low around 73. Calm wind.

    Low: 73 °F

    Patchy Fog

  • Wednesday

    Wednesday: Patchy fog before 7am. Otherwise, mostly sunny, with a high near 88. Heat index values as high as 97. Calm wind becoming south 5 to 7 mph in the afternoon.

    High: 88 °F

    Patchy Fog
    then Sunny

  • Wednesday Night

    Wednesday Night: A 30 percent chance of showers and thunderstorms, mainly between 2am and 5am. Mostly cloudy, with a low around 75. Southwest wind 6 to 8 mph.

    Low: 75 °F

    Mostly Cloudy
    then Chance
    Showers

  • Thursday

    Thursday: A 50 percent chance of showers and thunderstorms, mainly after 8am. Partly sunny, with a high near 88. Heat index values as high as 98. Southwest wind 7 to 11 mph.

    High: 88 °F

    Chance
    T-storms

  • Thursday Night

    Thursday Night: Partly cloudy, with a low around 75. Southwest wind around 8 mph.

    Low: 75 °F

    Partly Cloudy

  • Friday

    Friday: Sunny, with a high near 87.

    High: 87 °F

    Sunny

  • Friday Night

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

    Low: 68 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 84.

    High: 84 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: A 30 percent chance of showers after 2am. Mostly cloudy, with a low around 70.

    Low: 70 °F

    Mostly Cloudy
    then Chance
    Showers

Detailed Forecast

Overnight
Patchy fog after 5am. Otherwise, partly cloudy, with a low around 73. Calm wind.
Wednesday
Patchy fog before 7am. Otherwise, mostly sunny, with a high near 88. Heat index values as high as 97. Calm wind becoming south 5 to 7 mph in the afternoon.
Wednesday Night
A 30 percent chance of showers and thunderstorms, mainly between 2am and 5am. Mostly cloudy, with a low around 75. Southwest wind 6 to 8 mph.
Thursday
A 50 percent chance of showers and thunderstorms, mainly after 8am. Partly sunny, with a high near 88. Heat index values as high as 98. Southwest wind 7 to 11 mph.
Thursday Night
Partly cloudy, with a low around 75. Southwest wind around 8 mph.
Friday
Sunny, with a high near 87.
Friday Night
Partly cloudy, with a low around 68.
Saturday
Mostly sunny, with a high near 84.
Saturday Night
A 30 percent chance of showers after 2am. Mostly cloudy, with a low around 70.
Sunday
A chance of showers, with thunderstorms also possible after 2pm. Mostly cloudy, with a high near 85. Chance of precipitation is 50%.
Sunday Night
A chance of thunderstorms. Mostly cloudy, with a low around 70. Chance of precipitation is 30%.
Monday
Mostly sunny, with a high near 84.
Monday Night
Partly cloudy, with a low around 68.
Tuesday
Mostly sunny, with a high near 83.
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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:
2:02 am EDT Jul 16, 2025
Forecast Valid:
3am EDT Jul 16, 2025-6pm EDT Jul 22, 2025
 
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