I don't know about at sea, but I have been to NY, Boston and Maine in June. The weather can be very warm in NY ( I saw women sunbathing in bikinis in March in 2010!) The weather further north, in Maine is usually pleasantly warm in June, while July and August can be very hot. I go to Maine a lot as my son lives there. Maine is on a level with Montreal, Canada. We drove there one year. It depends on what part of Canada, your DH is going to BJ. I hope to visit NY and New Jersey more, where my nephew is now living. I would love to travel by sea to NY. Sounds exciting.