Did an 11-day Fall Foliage cruise a couple of years ago (roundtrip Boston to Quebec), mid-Oct, on the way to Quebec water was a little choppy, not too bad, but it was extremely windy. On the way back to Boston, we got into a North-Atlantic winter storm, over 60ft waves and 90 mile an hour winds for over 48hrs.
It was something else!!! If you saw the movie Perfect Storm, this happened at the same place. They said it was unusual at that time of year, but it could happen. We were on the Splendour of the Seas, and the ship handled it very well.