Atlantic water temps are much warmer in the Fall than Spring, as it's had the full summer season to warm up after the winter time and temps haven't cooled down much yet. Just looked at a Bermuda water temp monthly chart. July, August, Sept. average is around 83F, June and October is 78F. May is 73F.
Lol, we visit a beach in Maine in the summer--so all these water temps seem really warm to me! The highest it ever gets there is about 66F in August!