Nantucket water temperature by month

Swimmable from July through August.

Month by month

Month Typical Feels
January 38° brisk
February 37° brisk
March 42° brisk
April 50° brisk
May 58° brisk
June 67° refreshing
July 75° perfect
August 74° perfect
September 69° refreshing
October 60° brisk
November 50° brisk
December 41° brisk

The year at a glance

swimmable 30° 40° 50° 60° 70° 80° 75° 37° JFMAMJJASOND January: typically 38° — brisk February: typically 37° — brisk March: typically 42° — brisk April: typically 50° — brisk May: typically 58° — brisk June: typically 67° — refreshing July: typically 75° — perfect August: typically 74° — perfect September: typically 69° — refreshing October: typically 60° — brisk November: typically 50° — brisk December: typically 41° — brisk

The water right now

Typically about 60° in October — brisk.

from the Nantucket harbor station, about a mile from the sand

brisk

bath-warm 80° and up perfect 72–79° refreshing 65–71° brisk below 65° 60° typical for October

The reading comes from the harbor, where Jetties and Children's Beach are. Ride out to Surfside or Cisco and the open Atlantic runs several degrees colder.

About this reading

The Nantucket harbor station sits in the harbor; open-water surf can read a few degrees different.

Reading from the Nantucket harbor station, about a mile from the sand.

Warm water says nothing about surf, rip currents, or bacteria — check local lifeguard flags and advisories.