It's cool in the mornings this time of year on Cape Cod.
In the evening, too. People who remember when Cape Cod had real seasons, because it didn't have a substantial year-round population, remember what it's like to be in a lonesome cottage by the shore before the tourists show up. The tourists live there all the time now. And it's never cold because the houses are modern and weather is something you watch on television.
The old-fashioned locals know that summer doesn't begin, really, until July Fourth. Memorial Day is a head fake. You might as well swim at the Arctic Circle as Nauset in May or June.
Locals don't swim, anyway. They have boats, and sit by the fire in the evening, or in the morning in the milky early sunshine, and wait for the visitors to come. Or to go.