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.

Overcast

50°F

10°C

Humidity 89%
Wind Speed SW 3 mph
Barometer 29.75 in (1007.6 mb)
Dewpoint 47°F (8°C)
Visibility 10.00 mi
Last update 30 Apr 10:56 am EDT
Extended Forecast for

Great River NY

  • Today

    Today: Cloudy, then gradually becoming mostly sunny, with a high near 59. East wind around 6 mph becoming northwest in the afternoon.

    High: 59 °F

    Decreasing
    Clouds

  • Tonight

    Tonight: Partly cloudy, with a low around 45. Northwest wind around 6 mph.

    Low: 45 °F

    Partly Cloudy

  • Friday

    Friday: Sunny, with a high near 61. West wind 9 to 11 mph.

    High: 61 °F

    Sunny

  • Friday Night

    Friday Night: A 20 percent chance of showers after 2am. Mostly cloudy, with a low around 46. Southwest wind 5 to 7 mph.

    Low: 46 °F

    Partly Cloudy
    then Slight
    Chance
    Showers

  • Saturday

    Saturday: A 40 percent chance of rain, mainly after 2pm. Mostly cloudy, with a high near 56. Light and variable wind becoming south 5 to 8 mph in the morning.

    High: 56 °F

    Chance Rain

  • Saturday Night

    Saturday Night: A 50 percent chance of rain. Mostly cloudy, with a low around 44.

    Low: 44 °F

    Chance Rain

  • Sunday

    Sunday: Mostly sunny, with a high near 58.

    High: 58 °F

    Mostly Sunny

  • Sunday Night

    Sunday Night: Mostly clear, with a low around 44.

    Low: 44 °F

    Mostly Clear

  • Monday

    Monday: Mostly sunny, with a high near 59. Breezy.

    High: 59 °F

    Sunny then
    Mostly Sunny
    and Breezy

Detailed Forecast

Today
Cloudy, then gradually becoming mostly sunny, with a high near 59. East wind around 6 mph becoming northwest in the afternoon.
Tonight
Partly cloudy, with a low around 45. Northwest wind around 6 mph.
Friday
Sunny, with a high near 61. West wind 9 to 11 mph.
Friday Night
A 20 percent chance of showers after 2am. Mostly cloudy, with a low around 46. Southwest wind 5 to 7 mph.
Saturday
A 40 percent chance of rain, mainly after 2pm. Mostly cloudy, with a high near 56. Light and variable wind becoming south 5 to 8 mph in the morning.
Saturday Night
A 50 percent chance of rain. Mostly cloudy, with a low around 44.
Sunday
Mostly sunny, with a high near 58.
Sunday Night
Mostly clear, with a low around 44.
Monday
Mostly sunny, with a high near 59. Breezy.
Monday Night
Partly cloudy, with a low around 51.
Tuesday
Mostly sunny, with a high near 63. Breezy.
Tuesday Night
Mostly cloudy, with a low around 51.
Wednesday
A 40 percent chance of showers. Partly sunny, with a high near 63.
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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:
4:33 am EDT Apr 30, 2026
Forecast Valid:
11am EDT Apr 30, 2026-6pm EDT May 6, 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