Black sand
Madorra
Panxón, Nigrán, Spain · sea 17.2 °C at its warmest, in August

Sea temperature month by month
Monthly means in °C, NOAA OISST v2.1 climatology 1991–2020.
About
La Playa de Madorra es una playa situada en la localidad pontevedresa de Nigrán (Galicia, España), parroquia de Panjón. Se encuentra entre la Playa de Panjón y la Playa Area Fofa.
Questions
How warm is the sea at Madorra?
The sea off Madorra averages 17.2 °C at its warmest, in August, and 13.2 °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 Madorra?
The sea here never averages 20 °C in any month, so swimming means cold water all year. Some people do it anyway.
Where is Madorra?
Madorra is on the coast of Panxón, Nigrán, Spain, at 42.1458, -8.8257. The map on this site flies straight to it.