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.

Mostly Cloudy

72°F

22°C

Humidity 94%
Wind Speed N 7 mph
Barometer 30.03 in (1016.8 mb)
Dewpoint 70°F (21°C)
Visibility 10.00 mi
Last update 18 Sep 6:56 am EDT
Extended Forecast for

Great River NY

  • Today

    Today: Mostly sunny, with a high near 79. North wind 8 to 11 mph.

    High: 79 °F

    Mostly Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 58. North wind 9 to 15 mph.

    Low: 58 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 68. Northeast wind 9 to 14 mph.

    High: 68 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 60. East wind around 9 mph.

    Low: 60 °F

    Mostly Cloudy

  • Sunday

    Sunday: Showers likely, mainly after 2pm. Mostly cloudy, with a high near 70. Southeast wind 10 to 13 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 70 °F

    Slight Chance
    Showers then
    Showers
    Likely

  • Sunday Night

    Sunday Night: Showers. Low around 62. Chance of precipitation is 90%. New precipitation amounts between 1 and 2 inches possible.

    Low: 62 °F

    Showers

  • Monday

    Monday: Showers likely, mainly before 8am. Mostly cloudy, with a high near 68. Chance of precipitation is 60%.

    High: 68 °F

    Showers
    Likely

  • Monday Night

    Monday Night: A 50 percent chance of showers. Mostly cloudy, with a low around 58. Breezy.

    Low: 58 °F

    Chance
    Showers and
    Breezy

  • Tuesday

    Tuesday: A 40 percent chance of showers. Mostly cloudy, with a high near 64. Windy.

    High: 64 °F

    Chance
    Showers and
    Windy

Detailed Forecast

Today
Mostly sunny, with a high near 79. North wind 8 to 11 mph.
Tonight
Partly cloudy, with a low around 58. North wind 9 to 15 mph.
Saturday
Mostly sunny, with a high near 68. Northeast wind 9 to 14 mph.
Saturday Night
Mostly cloudy, with a low around 60. East wind around 9 mph.
Sunday
Showers likely, mainly after 2pm. Mostly cloudy, with a high near 70. Southeast wind 10 to 13 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.
Sunday Night
Showers. Low around 62. Chance of precipitation is 90%. New precipitation amounts between 1 and 2 inches possible.
Monday
Showers likely, mainly before 8am. Mostly cloudy, with a high near 68. Chance of precipitation is 60%.
Monday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 58. Breezy.
Tuesday
A 40 percent chance of showers. Mostly cloudy, with a high near 64. Windy.
Tuesday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 57. Windy.
Wednesday
A 30 percent chance of showers. Mostly cloudy, with a high near 65. Windy.
Wednesday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 57. Windy.
Thursday
A 30 percent chance of showers. Partly sunny, with a high near 66. Windy.
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Forecast Area
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ABOUT THIS FORECAST

 
Point Forecast:
Great River NY
 40.7°N 73.17°W (Elev. 7 ft)
Last Update:
5:16 am EDT Sep 18, 2026
Forecast Valid:
7am EDT Sep 18, 2026-6pm EDT Sep 24, 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