Nantucket Beach Water Temperature
Sea-surface temperature at Nantucket Beach, Massachusetts · times in EDT
Updated 7:03 AM EDT
How it compares today
Water temperature through the year
Monthly normals computed from 2023–2025 daily sea-surface temperature history.
Nearby water right now
7-day outlook
| Day | Air high / low | Max UV | Rain |
|---|---|---|---|
| Fri, Aug 28 | 79° / 70° | 7 | 12% |
| Sat, Aug 29 | 73° / 65° | 7 | 2% |
| Sun, Aug 30 | 73° / 66° | 7 | 21% |
| Mon, Aug 31 | 75° / 68° | 6 | 38% |
| Tue, Sep 1 | 69° / 64° | 2 | 35% |
| Wed, Sep 2 | 72° / 65° | 4 | 39% |
| Thu, Sep 3 | 75° / 72° | 6 | 36% |
Sea-surface temperature and wave data from the Open-Meteo marine model; weather from Open-Meteo.
Is Nantucket Beach warm enough to swim?
At 70°F, the water at Nantucket Beach is cool but swimmable. Most swimmers are comfortable without a wetsuit above 72°F; below 62°F, cold-water shock becomes a real risk for unprotected swimmers.
That is 1° above the August average of 69°F here.
The water here never averages above 70°F — even in August, the warmest month, it sits around 69°F. Most people wear a wetsuit.
Frequently asked questions
How warm is the water at Nantucket Beach right now?
The sea-surface temperature is about 70°F. That is 1° above the August average of 69°F here.
When is the water warm enough to swim at Nantucket Beach?
The water here never averages above 70°F — even in August, the warmest month, it sits around 69°F. Most people wear a wetsuit.
What is the warmest the water gets at Nantucket Beach?
Around 69°F in August, based on 2023–2025 records. The coolest month is February at roughly 39°F.