Water temperature in Islip in December
Is it warm enough to swim in Islip in December? Average water temperature in Islip in December is 47.7°F and therefore is not suitable for comfortable swimming. The warmest sea in Islip in December is 53.8°F, and the coldest is 40.1°F. Average high air temperature in Islip in December is 43°F, and average low temperature is 28°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in Islip
Changes water temperature in Islip in December 2025, 2024
To get an accurate forecast for the water temperature in Islip for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in Islip, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of December.
You can choose any other years:
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| December 1 | 48.9°F | 51.3°F | 42.1°F | 53.8°F |
| December 2 | 50.4°F | 51.1°F | 42.6°F | 53.6°F |
| December 3 | 48.6°F | 50.4°F | 43°F | 53.6°F |
| December 4 | 48°F | 49.8°F | 44.2°F | 53.2°F |
| December 5 | 48°F | 50°F | 43.5°F | 53.1°F |
| December 6 | 47.1°F | 49.5°F | 43.2°F | 53.1°F |
| December 7 | 46.4°F | 49.3°F | 43.5°F | 52.7°F |
| December 8 | 46°F | 49.8°F | 42.6°F | 52.5°F |
| December 9 | 46°F | 48.2°F | 43.2°F | 52.9°F |
| December 10 | 46.2°F | 48.4°F | 43.5°F | 52.7°F |
| December 11 | 46.2°F | 48.4°F | 45.1°F | 52.9°F |
| December 12 | 44.8°F | 47.8°F | 44.4°F | 52.7°F |
| December 13 | 45°F | 47.8°F | 43.3°F | 52.5°F |
| December 14 | 44.2°F | 47.7°F | 42.3°F | 52.7°F |
| December 15 | 42.8°F | 46.9°F | 42.3°F | 53.2°F |
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| December 16 | 43.2°F | 46.8°F | 42.3°F | 52.7°F |
| December 17 | 42.3°F | 47.5°F | 42.1°F | 52.5°F |
| December 18 | 42.8°F | 46.4°F | 42.8°F | 52°F |
| December 19 | 43°F | 46.9°F | 43°F | 51.3°F |
| December 20 | 43.5°F | 46.8°F | 42.6°F | 51.4°F |
| December 21 | 43.7°F | 46.2°F | 41.5°F | 51.3°F |
| December 22 | 43.2°F | 45.7°F | 41.7°F | 50.7°F |
| December 23 | 43.3°F | 45.7°F | 40.1°F | 50.5°F |
| December 24 | 43.5°F | 45°F | 40.3°F | 51.1°F |
| December 25 | 43.5°F | 43.5°F | 42.3°F | 50.5°F |
| December 26 | 43.3°F | 43.3°F | 42.6°F | 50.5°F |
| December 27 | 42.8°F | 43°F | 42.3°F | 50.7°F |
| December 28 | 41.5°F | 43.2°F | 41.5°F | 50.9°F |
| December 29 | 42.3°F | 43.2°F | 41.5°F | 50.9°F |
| December 30 | 41.4°F | 42.3°F | 41.4°F | 50.5°F |
| December 31 | 41.2°F | 40.6°F | 40.6°F | 50.7°F |
Average water temperature in Islip in December over a decade
| 2016 | 2017 | 2018 | 2019 | 2020 |
| 48°F | 49.5°F | 45.5°F | 45.9°F | 48.7°F |
| 2021 | 2022 | 2023 | 2024 | 2025 |
| 49.3°F | 47.1°F | 43°F | 46.9°F | 49.3°F |
Islip sea state in December
Chart comparing the height of waves in Islip in December over the past years. The red line indicates the height of the waves when swimming in the sea is prohibited. To view the current sea conditions, click on the graph.
Weather and climate in Islip in December
This data display average monthly climate indicators in Islip in December based on our historical weather readings over a period of ten years. In addition to temperature, we include data on the number of rainy and sunny days so you can have all the information about your destination before your trip
- Average HIGH temperature43°F
- Average LOW temperature28°F
- Average rainfall days11 days
- Average rainfall104mm/4.1''
- Average snowfall137mm/5.4''
Islip water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
