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

78°F

26°C

Humidity 60%
Wind Speed NW 16 mph
Barometer 30.06 in (1017.7 mb)
Dewpoint 63°F (17°C)
Visibility 10.00 mi
Heat Index80°F (27°C)
Last update 18 Sep 11:56 am EDT
Extended Forecast for

Great River NY

  • This Afternoon

    This Afternoon: Sunny, with a high near 77. North wind around 10 mph.

    High: 77 °F

    Sunny

  • Tonight

    Tonight: Partly cloudy, with a low around 58. North wind 10 to 16 mph.

    Low: 58 °F

    Partly Cloudy

  • Saturday

    Saturday: Mostly sunny, with a high near 67. Northeast wind 10 to 16 mph.

    High: 67 °F

    Mostly Sunny

  • Saturday Night

    Saturday Night: Mostly cloudy, with a low around 62. Southeast wind around 10 mph.

    Low: 62 °F

    Mostly Cloudy

  • Sunday

    Sunday: Showers likely, mainly after 2pm. Mostly cloudy, with a high near 69. South wind 11 to 17 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.

    High: 69 °F

    Slight Chance
    Showers then
    Showers
    Likely

  • Sunday Night

    Sunday Night: Showers. Low around 64. Chance of precipitation is 90%. New precipitation amounts between 1 and 2 inches possible.

    Low: 64 °F

    Showers

  • Monday

    Monday: Showers likely, mainly before 8am. Mostly cloudy, with a high near 67. Breezy. Chance of precipitation is 60%.

    High: 67 °F

    Showers
    Likely and
    Breezy

  • Monday Night

    Monday Night: A 50 percent chance of showers. Mostly cloudy, with a low around 60. Breezy.

    Low: 60 °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

This Afternoon
Sunny, with a high near 77. North wind around 10 mph.
Tonight
Partly cloudy, with a low around 58. North wind 10 to 16 mph.
Saturday
Mostly sunny, with a high near 67. Northeast wind 10 to 16 mph.
Saturday Night
Mostly cloudy, with a low around 62. Southeast wind around 10 mph.
Sunday
Showers likely, mainly after 2pm. Mostly cloudy, with a high near 69. South wind 11 to 17 mph. Chance of precipitation is 70%. New precipitation amounts between a tenth and quarter of an inch possible.
Sunday Night
Showers. Low around 64. 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 67. Breezy. Chance of precipitation is 60%.
Monday Night
A 50 percent chance of showers. Mostly cloudy, with a low around 60. 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 58. Windy.
Wednesday
A 30 percent chance of showers. Mostly cloudy, with a high near 64. Windy.
Wednesday Night
A 40 percent chance of showers. Mostly cloudy, with a low around 58. Windy.
Thursday
A 30 percent chance of showers. Mostly cloudy, with a high near 65. Windy.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Great River NY
 40.7°N 73.14°W (Elev. 0 ft)
Last Update:
11:03 am EDT Sep 18, 2026
Forecast Valid:
12pm 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