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.

Light Snow

37°F

3°C

Humidity 76%
Wind Speed SW 10 G 20 mph
Barometer 30.01 in (1016.3 mb)
Dewpoint 30°F (-1°C)
Visibility 3.00 mi
Wind Chill30°F (-1°C)
Last update 17 Jan 1:56 pm EST
Extended Forecast for

Port Jefferson NY

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

  • This Afternoon

    This Afternoon: Rain before 3pm, then rain and snow. Steady temperature around 37. Southwest wind 11 to 13 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.

    High: 37 °F

    Rain/Snow

  • Tonight

    Tonight: A chance of snow before 7pm, then a chance of snow after 1am. Mostly cloudy, with a low around 33. West wind 5 to 11 mph. Chance of precipitation is 40%.

    Low: 33 °F

    Chance Snow

  • Sunday

    Sunday: Periods of snow, mainly after 7am. High near 34. West wind 5 to 7 mph becoming northeast in the afternoon. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.

    High: 34 °F

    Snow

  • Sunday Night

    Sunday Night: A 40 percent chance of snow before 1am. Cloudy, then gradually becoming partly cloudy, with a low around 27. Wind chill values between 20 and 25. North wind 8 to 10 mph becoming northwest after midnight.

    Low: 27 °F

    Chance Snow

  • M.L.King Day

    M.L.King Day: Mostly sunny, with a high near 33. Breezy, with a west wind 13 to 22 mph.

    High: 33 °F

    Mostly Sunny
    then Mostly
    Sunny and
    Breezy

  • Monday Night

    Monday Night: Partly cloudy, with a low around 21. Breezy.

    Low: 21 °F

    Partly Cloudy
    and Breezy

  • Tuesday

    Tuesday: Mostly sunny, with a high near 24.

    High: 24 °F

    Mostly Sunny

  • Tuesday Night

    Tuesday Night: Mostly clear, with a low around 18.

    Low: 18 °F

    Mostly Clear

  • Wednesday

    Wednesday: Mostly sunny, with a high near 37.

    High: 37 °F

    Mostly Sunny

Detailed Forecast

This Afternoon
Rain before 3pm, then rain and snow. Steady temperature around 37. Southwest wind 11 to 13 mph. Chance of precipitation is 80%. Little or no snow accumulation expected.
Tonight
A chance of snow before 7pm, then a chance of snow after 1am. Mostly cloudy, with a low around 33. West wind 5 to 11 mph. Chance of precipitation is 40%.
Sunday
Periods of snow, mainly after 7am. High near 34. West wind 5 to 7 mph becoming northeast in the afternoon. Chance of precipitation is 80%. New snow accumulation of 1 to 3 inches possible.
Sunday Night
A 40 percent chance of snow before 1am. Cloudy, then gradually becoming partly cloudy, with a low around 27. Wind chill values between 20 and 25. North wind 8 to 10 mph becoming northwest after midnight.
M.L.King Day
Mostly sunny, with a high near 33. Breezy, with a west wind 13 to 22 mph.
Monday Night
Partly cloudy, with a low around 21. Breezy.
Tuesday
Mostly sunny, with a high near 24.
Tuesday Night
Mostly clear, with a low around 18.
Wednesday
Mostly sunny, with a high near 37.
Wednesday Night
Mostly cloudy, with a low around 32.
Thursday
Mostly cloudy, with a high near 37.
Thursday Night
Partly cloudy, with a low around 23.
Friday
Mostly sunny, with a high near 32.
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Forecast Area
Tiles ©ESRI

ABOUT THIS FORECAST

 
Point Forecast:
Port Jefferson NY
 40.96°N 73.08°W (Elev. 3 ft)
Last Update:
1:04 pm EST Jan 17, 2026
Forecast Valid:
2pm EST Jan 17, 2026-6pm EST Jan 23, 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