This data the coastal Islip 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 Islip today is 72°F. Based on our historical data over a period of ten years, the warmest water in this day in the Atlantic Ocean near Islip was recorded in 2018 and was 77.4°F, and the coldest was recorded in 2017 at 68.7°F. Sea water temperature in Islip is expected to drop to 71.4°F in the next 10 days. September average water temperature in Islip is 70.9°F, the minimum temperature is 62.2°F, and the maximum is 80.1°F.
The swimming season in Islip lasts from June to September. During those months, Islip water temperature does not drop below 68°F and therefore suitable for comfortable swimming. The average water temperature in Islip in winter reaches 42.8°F, in spring 47.5°F, in summer the average temperature rises to 71.2°F, and in autumn it is 63.3°F.
September 5, 2025 |
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today temp |
72°F |
September 4, 2025 |
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yesterday temp |
70.9°F |
The sea salinity in Islip is 29.78‰, 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 Islip. 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 Islip. 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 |
---|---|---|---|
3' 1" | 2' 11" | 3' 1" | 3' 0" |
0.94 m | 0.89 m | 0.93 m | 0.91 m |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
2' 10" | 2' 11" | 3' 8" | 4' 0" |
0.87 m | 0.9 m | 1.12 m | 1.21 m |
Data in a table show Islip temperature today (September 5, 2025). For more information and forecast for a few days, go to the weather forecast Islip.
0-3 h | 3-6 h | 6-9 h | 9-12 h |
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![]() | ![]() | ![]() | ![]() |
69.3°F | 69.3°F | 69.4°F | 71.8°F |
12-15 h | 15-18 h | 18-21 h | 21-24 h |
---|---|---|---|
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80.2°F | 79.9°F | 76.5°F | 73.9°F |
You may also be interested in other sections of our site for Islip: Sunrise and Sunset, Tides
These figures shows the average, minimum and maximum monthly sea temperature in Islip. 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 Islip 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 | 41.7°F | 30°F | 49.8°F | cold |
Sea water temperature in Islip in January | ||||
February | 38.8°F | 32.7°F | 44.4°F | cold |
Sea water temperature in Islip in February | ||||
March | 40.8°F | 32.4°F | 50.2°F | cold |
Sea water temperature in Islip in March | ||||
April | 46.6°F | 37.6°F | 55.9°F | cold |
Sea water temperature in Islip in April | ||||
May | 54.9°F | 46.4°F | 66.4°F | cold |
Sea water temperature in Islip in May | ||||
June | 65.1°F | 54.5°F | 77.9°F | cold |
Sea water temperature in Islip in June | ||||
July | 74.1°F | 65.8°F | 83.7°F | warm |
Sea water temperature in Islip in July | ||||
August | 74.5°F | 67.6°F | 82.9°F | warm |
Sea water temperature in Islip in August | ||||
September | 70.9°F | 62.2°F | 80.1°F | warm |
Sea water temperature in Islip in September | ||||
October | 63.7°F | 56.1°F | 77.4°F | cold |
Sea water temperature in Islip in October | ||||
November | 55.2°F | 41.7°F | 62.8°F | cold |
Sea water temperature in Islip in November | ||||
December | 47.7°F | 40.1°F | 53.8°F | cold |
Sea water temperature in Islip in December |