Summer into fall has the best diving when the Gulf Stream is also closer to shore but that’s also hurricane season and it didn’t become the "Graveyard of the Atlantic" by having nice weather :(
I have been blown out of a few dives there but never a whole trip. If it’s bad offshore then they dive shallow, once we had a wild ride thru a thunderstorm to dive offshore. One day the morning was rough so we toured an old fort and went out in the afternoon and one day it actually looked like a pond :)