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.

Fog/Mist

28°F

-2°C

Humidity 96%
Wind Speed Calm
Barometer 30.09 in (1019.1 mb)
Dewpoint 27°F (-3°C)
Visibility 3.00 mi
Last update 18 Jan 12:56 am EST
Extended Forecast for

Stony Brook NY

Winter Weather Advisory January 18, 10:00am until January 18, 10:00pm
Click here for hazard details and duration
Winter Weather Advisory

  • Overnight

    Overnight: A 40 percent chance of snow after 4am. Areas of freezing fog. Mostly cloudy, with a low around 31. Calm wind.

    Low: 31 °F

    Chance Snow
    and Areas
    Freezing Fog

  • Sunday

    Sunday: Snow, possibly mixed with rain, becoming all snow after 4pm. High near 36. Calm wind becoming northeast around 6 mph in the afternoon. Chance of precipitation is 90%. New snow accumulation of less than one inch possible.

    High: 36 °F

    Rain/Snow

  • Sunday Night

    Sunday Night: Snow, mainly before 10pm. Low around 23. Wind chill values between 15 and 20. North wind 6 to 8 mph becoming west after midnight. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible.

    Low: 23 °F

    Snow then
    Chance Snow

  • M.L.King Day

    M.L.King Day: Mostly sunny, with a high near 32. Wind chill values between 15 and 20. Breezy, with a southwest wind 9 to 14 mph increasing to 15 to 20 mph in the afternoon.

    High: 32 °F

    Mostly Sunny
    then Mostly
    Sunny and
    Breezy

  • Monday Night

    Monday Night: Partly cloudy, with a low around 17. West wind 15 to 18 mph.

    Low: 17 °F

    Partly Cloudy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 24. Breezy.

    High: 24 °F

    Mostly Sunny
    and Breezy

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 14.

    Low: 14 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 37.

    High: 37 °F

    Mostly Sunny

  • Wednesday Night

    Wednesday Night: Mostly cloudy, with a low around 28.

    Low: 28 °F

    Mostly Cloudy

Detailed Forecast

Overnight
A 40 percent chance of snow after 4am. Areas of freezing fog. Mostly cloudy, with a low around 31. Calm wind.
Sunday
Snow, possibly mixed with rain, becoming all snow after 4pm. High near 36. Calm wind becoming northeast around 6 mph in the afternoon. Chance of precipitation is 90%. New snow accumulation of less than one inch possible.
Sunday Night
Snow, mainly before 10pm. Low around 23. Wind chill values between 15 and 20. North wind 6 to 8 mph becoming west after midnight. Chance of precipitation is 80%. New snow accumulation of 2 to 4 inches possible.
M.L.King Day
Mostly sunny, with a high near 32. Wind chill values between 15 and 20. Breezy, with a southwest wind 9 to 14 mph increasing to 15 to 20 mph in the afternoon.
Monday Night
Partly cloudy, with a low around 17. West wind 15 to 18 mph.
Tuesday
Mostly sunny, with a high near 24. Breezy.
Tuesday Night
Mostly clear, with a low around 14.
Wednesday
Mostly sunny, with a high near 37.
Wednesday Night
Mostly cloudy, with a low around 28.
Thursday
Partly sunny, with a high near 37.
Thursday Night
Partly cloudy, with a low around 21.
Friday
Mostly sunny, with a high near 34.
Friday Night
Mostly cloudy, with a low around 26.
Saturday
A chance of rain and snow. Mostly cloudy, with a high near 36. Chance of precipitation is 30%.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Stony Brook NY
 40.92°N 73.15°W (Elev. 36 ft)
Last Update:
1:04 am EST Jan 18, 2026
Forecast Valid:
1am EST Jan 18, 2026-6pm EST Jan 24, 2026
 
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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