Beach
Deauville beach
France · sea 19 °C at its warmest, in August

Sea temperature month by month
8.2Jan
7.5Feb
8Mar
9.9Apr
12.4May
15.2Jun
17.7Jul
19Aug
18Sep
15.7Oct
12.8Nov
10Dec
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020.
About
beach in 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 Deauville beach?
The sea off Deauville beach averages 19 °C at its warmest, in August, and 7.5 °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 Deauville beach?
The sea here never averages 20 °C in any month, so swimming means cold water all year. Some people do it anyway.
Where is Deauville beach?
Deauville beach is on the coast of France, at 49.3604, 0.0644. The map on this site flies straight to it.