Beach
Notre-Dame Beach
Hyères, France · sea 23.5 °C at its warmest, in August

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020, sampled 15 km offshore, at the nearest open water cell of a 0.25° grid.
About
beach in Porquerolles, 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 Notre-Dame Beach?
The sea off Notre-Dame Beach averages 23.5 °C at its warmest, in August, and 13.3 °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 Notre-Dame Beach?
The sea reaches 20 °C or more from June to September. Twenty degrees is where most swimmers stop calling water cold; below it, a wetsuit helps.
Where is Notre-Dame Beach?
Notre-Dame Beach is on the coast of Hyères, France, at 43.0118, 6.2339. The map on this site flies straight to it.