As a New Englander, my advise is you should plan on the weather being pretty cool if not cold especially at sea and in the port towns. However, as the days wear on, temperatures will rise in the 50 to 60's. As in every cruise, try not to schedule too much. Take a half day tour in the morning then return for lunch on board and walk around the port cities during the afternoon. Peggy's Cove is one of my favority scenic stops near Quebec. There are good local tours too, which you could catch if time allowed. Portland, ME I would drive up the coast to Damiscotta to the most picturesque lighthouse that I know of. Stay off the rocks! It can be dangerous. You could easily rent a car for that one. Take a ship's tour if your ship stops at Bar Harbor to Arcadia National Park. Don't forget hat and gloves, just in case the weather turns raw. If you stop in Boston, just take a Trolley tour and get on and off at places that interest you.
Bon Voyage