Summer and Fall when does one start and another begin

Since when does school start in the middle of August? Isn't August designed to be the hottest month for outdoor swimming and beach fun? I always thought when school started that was the beginning of fall and the end of Summer.

Living in California our Summer usually goes all the way through September and sometimes October. Out on the Coast the best time to visit are the outlying months of all seasons....early spring and late summer are so beautiful and still hold all of the beauty of the actual meat of the season with less traffic and people to navigate. I love the Northern California Coast because it feels like I am part of an exclusive group that few are invited to be a part of. I know that once the smell of salty air and a cool breeze hits my face that Summer is very much still here and there is no end in sight.