Beach
Plage des Chevrets
Saint-Coulomb, France · sea 18.1 °C at its warmest, in August

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020, sampled 16 km offshore, at the nearest open water cell of a 0.25° grid.
About
beach in Saint-Coulomb, France
Wikipedia has no article about this beach yet. It is on the atlas from its Wikidata record and its photograph.
Questions
How warm is the sea at Plage des Chevrets?
The sea off Plage des Chevrets averages 18.1 °C at its warmest, in August, and 8.5 °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 Plage des Chevrets?
The sea here never averages 20 °C in any month, so swimming means cold water all year. Some people do it anyway.
Where is Plage des Chevrets?
Plage des Chevrets is on the coast of Saint-Coulomb, France, at 48.6942, -1.9375. The map on this site flies straight to it.