Water temperature in Islip in January
Is it warm enough to swim in Islip in January? Average water temperature in Islip in January is 41.7°F and therefore is not suitable for comfortable swimming. The warmest sea in Islip in January is 49.8°F, and the coldest is 30°F. Average high air temperature in Islip in January is 38°F, and average low temperature is 23°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 January 2026, 2025
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 January.
You can choose any other years:
| Day | 2026 | 2025 | Min | Max |
|---|---|---|---|---|
| January 1 | 40.5°F | 41.9°F | 40.5°F | 49.8°F |
| January 2 | 40.8°F | 41.2°F | 40.5°F | 49.3°F |
| January 3 | 40.5°F | 42.4°F | 40.5°F | 49.1°F |
| January 4 | 40.5°F | 41.9°F | 39.9°F | 48.4°F |
| January 5 | 40.3°F | 41.4°F | 40.3°F | 47.8°F |
| January 6 | 39.7°F | 41.5°F | 39.7°F | 47.8°F |
| January 7 | 39.6°F | 41.2°F | 39.6°F | 47.5°F |
| January 8 | 37.9°F | 40.8°F | 37.9°F | 47.7°F |
| January 9 | 41.2°F | 39.2°F | 47.5°F | |
| January 10 | 40.1°F | 38.8°F | 47.3°F | |
| January 11 | 40.6°F | 38.8°F | 47.1°F | |
| January 12 | 39.4°F | 39°F | 46.8°F | |
| January 13 | 39.9°F | 39.2°F | 46.8°F | |
| January 14 | 39.6°F | 38.5°F | 46.6°F | |
| January 15 | 39.9°F | 37.9°F | 46.4°F |
| Day | 2026 | 2025 | Min | Max |
|---|---|---|---|---|
| January 16 | 39.6°F | 37.8°F | 46.4°F | |
| January 17 | 39.9°F | 36.9°F | 45.7°F | |
| January 18 | 39°F | 34.5°F | 45.3°F | |
| January 19 | 37.2°F | 33.6°F | 45.3°F | |
| January 20 | 38.5°F | 33.3°F | 45.3°F | |
| January 21 | 38.1°F | 31.6°F | 45.7°F | |
| January 22 | 37°F | 30°F | 44.8°F | |
| January 23 | 37.2°F | 31.3°F | 44.4°F | |
| January 24 | 36.7°F | 32.5°F | 44.4°F | |
| January 25 | 36.1°F | 33.4°F | 44.2°F | |
| January 26 | 36.9°F | 35.2°F | 43.7°F | |
| January 27 | 35.6°F | 35.6°F | 45°F | |
| January 28 | 34.9°F | 34.9°F | 44.6°F | |
| January 29 | 34.9°F | 34.9°F | 44.2°F | |
| January 30 | 35.6°F | 35.6°F | 43.9°F | |
| January 31 | 36.3°F | 36.3°F | 43.5°F |
Average water temperature in Islip in January over a decade
| 2016 | 2017 | 2018 | 2019 | 2020 |
| 44.2°F | 43°F | 38.8°F | 41°F | 42.6°F |
| 2021 | 2022 | 2023 | 2024 | 2025 |
| 42.1°F | 41.5°F | 42.8°F | 38.1°F | 39°F |
Islip sea state in January
Chart comparing the height of waves in Islip in January 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 January
This data display average monthly climate indicators in Islip in January 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 temperature38°F
- Average LOW temperature23°F
- Average rainfall days11 days
- Average rainfall91mm/3.6''
- Average snowfall170mm/6.7''
Islip water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
