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.

A Few Clouds

77°F

25°C

Humidity 94%
Wind Speed SW 5 mph
Barometer 30.05 in (1017.6 mb)
Dewpoint 75°F (24°C)
Visibility 10.00 mi
Heat Index78°F (26°C)
Last update 15 Jul 11:56 pm EDT
Extended Forecast for

Great River 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. Otherwise, partly cloudy, with a low around 73. Calm wind.

    Low: 73 °F

    Patchy Fog

  • Wednesday

    Wednesday: Mostly sunny, with a high near 83. Calm wind becoming south 5 to 9 mph in the morning.

    High: 83 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 74. Southwest wind around 8 mph.

    Low: 74 °F

    Chance
    T-storms

  • Thursday

    Thursday: A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2pm. Partly sunny, with a high near 84. Southwest wind 8 to 13 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

    High: 84 °F

    Showers
    Likely

  • Thursday Night

    Thursday Night: Showers likely and possibly a thunderstorm before 8pm. Partly cloudy, with a low around 76. Southwest wind 7 to 9 mph. Chance of precipitation is 60%.

    Low: 76 °F

    Showers
    Likely then
    Partly Cloudy

  • Friday

    Friday: Mostly sunny, with a high near 86.

    High: 86 °F

    Mostly Sunny

  • Friday Night

    Friday Night: Partly cloudy, with a low around 69.

    Low: 69 °F

    Partly Cloudy

  • Saturday

    Saturday: Sunny, with a high near 81.

    High: 81 °F

    Sunny

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 70.

    Low: 70 °F

    Mostly Cloudy

Detailed Forecast

Overnight
Patchy fog. Otherwise, partly cloudy, with a low around 73. Calm wind.
Wednesday
Mostly sunny, with a high near 83. Calm wind becoming south 5 to 9 mph in the morning.
Wednesday Night
A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 74. Southwest wind around 8 mph.
Thursday
A chance of showers and thunderstorms, then showers likely and possibly a thunderstorm after 2pm. Partly sunny, with a high near 84. Southwest wind 8 to 13 mph. Chance of precipitation is 60%. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.
Thursday Night
Showers likely and possibly a thunderstorm before 8pm. Partly cloudy, with a low around 76. Southwest wind 7 to 9 mph. Chance of precipitation is 60%.
Friday
Mostly sunny, with a high near 86.
Friday Night
Partly cloudy, with a low around 69.
Saturday
Sunny, with a high near 81.
Saturday Night
Mostly cloudy, with a low around 70.
Sunday
A 40 percent chance of showers after 8am. Partly sunny, with a high near 81.
Sunday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 70.
Monday
Mostly sunny, with a high near 83.
Monday Night
Partly cloudy, with a low around 69.
Tuesday
Mostly sunny, with a high near 80.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Great River NY
 40.72°N 73.16°W (Elev. 13 ft)
Last Update:
3:16 pm EDT Jul 15, 2025
Forecast Valid:
12am 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