Beach
Amorosa
Portugal · sea 17.3 °C at its warmest, in August

Sea temperature month by month
13.8Jan
13.3Feb
13.6Mar
14.3Apr
15.4May
16.6Jun
17.1Jul
17.3Aug
17.2Sep
16.7Oct
15.7Nov
14.5Dec
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 Amorosa?
The sea off Amorosa averages 17.3 °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 Amorosa?
The sea here never averages 20 °C in any month, so swimming means cold water all year. Some people do it anyway.
Where is Amorosa?
Amorosa is on the coast of Portugal, at 41.6478, -8.8258. The map on this site flies straight to it.