Beach
Shichirigahama
Kamakura, Japan · sea 25.9 °C at its warmest, in August

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020, sampled 22 km offshore, at the nearest open water cell of a 0.25° grid.
About
Shichirigahama (七里ヶ浜) is a beach near Kamakura, Kanagawa Prefecture, Japan, which goes from Koyurugimisaki Cape, near Fujisawa, to Inamuragasaki Cape, west of Kamakura.
Questions
How warm is the sea at Shichirigahama?
The sea off Shichirigahama averages 25.9 °C at its warmest, in August, and 15.2 °C at its coolest. These are monthly means from NOAA's OISST v2.1 satellite and buoy record for 1991 to 2020, sampled at the beach's own coordinates.
When can you swim at Shichirigahama?
The sea reaches 20 °C or more from June to November. Twenty degrees is where most swimmers stop calling water cold; below it, a wetsuit helps.
Where is Shichirigahama?
Shichirigahama is on the coast of Kamakura, Japan, at 35.3044, 139.5125. The map on this site flies straight to it.