Beach
Plages de Vielle Saint-Girons
Vielle-Saint-Girons, France · sea 21.9 °C at its warmest, in August

Sea temperature month by month
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 Plages de Vielle Saint-Girons?
The sea off Plages de Vielle Saint-Girons averages 21.9 °C at its warmest, in August, and 11.8 °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 Plages de Vielle Saint-Girons?
The sea reaches 20 °C or more from July to September. Twenty degrees is where most swimmers stop calling water cold; below it, a wetsuit helps.
Where is Plages de Vielle Saint-Girons?
Plages de Vielle Saint-Girons is on the coast of Vielle-Saint-Girons, France, at 43.9525, -1.3642. The map on this site flies straight to it.