Beach
Plage de la Malouine
Dinard, France · sea 18.1 °C at its warmest, in August

Sea temperature month by month
9.4Jan
8.5Feb
8.7Mar
10.2Apr
12.2May
14.7Jun
16.8Jul
18.1Aug
17.7Sep
15.9Oct
13.3Nov
11Dec
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020.
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 de la Malouine?
The sea off Plage de la Malouine 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 de la Malouine?
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 de la Malouine?
Plage de la Malouine is on the coast of Dinard, France, at 48.6398, -2.0595. The map on this site flies straight to it.