Hamptons Water Temperature by Month (NOAA Data)

Hamptons water is colder than the air makes you think. NOAA’s Montauk station averaged about 63 degrees in June, 71 in July and 72 in August over 2021 to 2025, and stayed above 68 only from July through September. October still averages 64 degrees, which is why fall swims are short.

The table below uses NOAA’s own hourly readings. The bay versus ocean guide explains why a bay beach can feel warmer than an ocean beach on the same day.

Where the numbers come from

NOAA’s Tides & Currents station 8510560 sits at Montauk and reports water temperature hourly. We averaged every hourly reading from 2021 through 2025 by month. The “range of yearly averages” column shows the coolest and warmest of the five yearly monthly averages. Some hours are missing, especially in 2021 and 2025, so averages use what NOAA recorded.

The warmest hourly reading in the five years was 80.2 degrees in August, and the coldest was 31.3 degrees in February. The station sits at the east end, so it is a guide to the region rather than a promise about any one beach; the Atlantic shore west of Montauk and the bay beaches can differ. We did not use offshore buoys, which measure open-ocean water.

What the temperatures mean

Our “feels like” column is a rule of thumb, not an official scale: under 50 degrees is wetsuit weather, 50 to 60 is cold with short dips, 60 to 68 is cool but fine for most people and 68 and up is comfortable. For surf, the season and swell guide pairs these temperatures with wetsuit thickness.

Planning a swim

If you want warm water, plan for late July through mid-September. For small children, a bay beach such as Foster Memorial Beach is the better choice in June.