Beach
Porto Katsiki
Greece · sea 25.9 °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
Porto Katsiki (Greek: Πόρτο Κατσίκι, "goat port") is a beach on the Ionian island of Lefkada, Greece. The name is said to be because formerly only goats could reach this area.
Questions
How warm is the sea at Porto Katsiki?
The sea off Porto Katsiki averages 25.9 °C at its warmest, in August, and 15.1 °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 Porto Katsiki?
The sea reaches 20 °C or more from June to November. Twenty degrees is where most swimmers stop calling water cold; below it, a wetsuit helps.
Where is Porto Katsiki?
Porto Katsiki is on the coast of Greece, at 38.6025, 20.5494. The map on this site flies straight to it.