Skiathos island, Banana beach, Greece.
Best seasons in Greece
Best season: April – June, September – mid October for sightseeing, though the seas (Ionian, Aegean, Mediterranean) will be chilly for swimming till May/June. The very, very best month for visiting the islands is September, with warm seas, fewer tourists and most ferry services still operating.
OK: mid July – August. But. . . the country is over heated, overcrowded and suffers the random Meltemi wind, making sea voyages wobbly and beach use uncomfortable.
Worst: Mid October-February is the cold, wet season so apart from a cool shuffle around Athens winter is to be avoided.