Beach
Playa di Castellammare
Castellammare del Golfo, Italy · sea 26.6 °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 Playa di Castellammare?
The sea off Playa di Castellammare averages 26.6 °C at its warmest, in August, and 14.4 °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 Playa di Castellammare?
The sea reaches 20 °C or more from June to October. Twenty degrees is where most swimmers stop calling water cold; below it, a wetsuit helps.
Where is Playa di Castellammare?
Playa di Castellammare is on the coast of Castellammare del Golfo, Italy, at 38.0243, 12.8988. The map on this site flies straight to it.