Mid May is wonderful in San Pedro. As Otter said if the sea Breezes quit on you then A/C is a must. But it is not oppressive.
November is my Favorite time.Hurricane season is over, the weather is Fantastic,and the water is still warm enough to enjoy all the activities you want.
No matter what time you decide to visit the one thing you can always count on is the wonderful people you will meet .
BTW: South Carolina is only miserable hot in , July/Aug/ Sept. after that it's Paradise.