This data the coastal Long Island sea water temperature today, tomorrow and the upcoming days. Besides, you can also get information about the weather and surf forecast, as well as the data on sunrise / sunset and moonrise / moonset at a given point on any given day.
Water temperature in Long Island today is 86°F. Based on our historical data over a period of ten years, the warmest water in this day in the Atlantic Ocean near Long Island was recorded in 2023 and was 86.9°F, and the coldest was recorded in 2008 at 82.6°F. Sea water temperature in Long Island is expected to drop to 84.9°F in the next 10 days. September average water temperature in Long Island is 85.1°F, the minimum temperature is 81.7°F, and the maximum is 87.1°F.
The swimming season in Long Island lasts from January to December, twelve months per year! During those months, Long Island water temperature does not drop below 68°F and therefore suitable for comfortable swimming. The average water temperature in Long Island in winter reaches 78.8°F, in spring 79°F, in summer the average temperature rises to 83.7°F, and in autumn it is 83.8°F.
September 5, 2025 |
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today temp |
86°F |
September 4, 2025 |
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yesterday temp |
85.3°F |
The sea salinity in Long Island is 36.91‰, and the average salinity of the World Ocean is 35‰.
Another important indicators for a comfortable holiday on the beach are the presence and height of the waves, as well as the speed and direction of the wind. Please find below data on the swell size for Long Island. We calculate the swell size based on the mean wave height (trough to crest) of each third highest wave. For more information on surf forecasts for the next ten days, please visit sea state forecast Long Island. Data in table shown for September 5, 2025, time in GMT 0 format (you can change the time zone on the sea state forecast page)
0-3 h | 3-6 h | 6-9 h | 9-12 h |
---|---|---|---|
1' 5" | 1' 6" | 1' 6" | 1' 6" |
0.44 m | 0.45 m | 0.45 m | 0.46 m |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
1' 7" | 1' 7" | 1' 7" | 1' 8" |
0.48 m | 0.48 m | 0.49 m | 0.5 m |
Data in a table show Long Island temperature today (September 5, 2025). For more information and forecast for a few days, go to the weather forecast Long Island.
0-3 h | 3-6 h | 6-9 h | 9-12 h |
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![]() | ![]() | ![]() | ![]() |
82.6°F | 82.8°F | 82.9°F | 83.1°F |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
![]() | ![]() | ![]() | ![]() |
84.6°F | 84.4°F | 84.2°F | 83.7°F |
You may also be interested in other sections of our site for Long Island: Sunrise and Sunset, Tides
These figures shows the average, minimum and maximum monthly sea temperature in Long Island. In addition to the table values, the graph below displays of changes average surface temperature during the year. Values are calculated based on the data over the past 10 years. Using them, you can check the water temperature in Long Island on any day of this period that interests you. Click on the month link and you will see a table for each day, or alternatively you can view the temperature curve of the month and select 2 different years you want to compare, either in a table or as a curve
Month | Avr | Min | Max | |
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January | 78.6°F | 75.7°F | 81°F | hot |
Sea water temperature in Long Island in January | ||||
February | 77.9°F | 74.8°F | 79.9°F | hot |
Sea water temperature in Long Island in February | ||||
March | 77.9°F | 73.9°F | 80.1°F | hot |
Sea water temperature in Long Island in March | ||||
April | 78.8°F | 75.4°F | 82.4°F | hot |
Sea water temperature in Long Island in April | ||||
May | 80.4°F | 76.8°F | 82.8°F | hot |
Sea water temperature in Long Island in May | ||||
June | 82.6°F | 79.2°F | 85.5°F | hot |
Sea water temperature in Long Island in June | ||||
July | 83.8°F | 81°F | 86.4°F | hot |
Sea water temperature in Long Island in July | ||||
August | 84.7°F | 82.6°F | 87.1°F | hot |
Sea water temperature in Long Island in August | ||||
September | 85.1°F | 81.7°F | 87.1°F | hot |
Sea water temperature in Long Island in September | ||||
October | 84.2°F | 81.3°F | 87.1°F | hot |
Sea water temperature in Long Island in October | ||||
November | 82°F | 78.4°F | 84.2°F | hot |
Sea water temperature in Long Island in November | ||||
December | 80.1°F | 76.3°F | 82.9°F | hot |
Sea water temperature in Long Island in December |