We are going in August to colonial Williamsburg. Might not be the best timing, but it's the best we can do. I bomb when it comes to planning around weather anyway. We went to the UP in Michigan this July. It was 28* at night and the day was swarming with the most mosquitos I've ever seen in my life. Not exactly a great summer vacation either. In fact the entire summer was so cold that we could hardly swim. I will always remember the summer of 2014 in pictures because we are all wearing sweatshirts in every vacation.
Looks like we'll get the opposite experience next year with heat and humidity.
I'm still looking forward to it.
Have fun.