Summer birthday girl here - July 20. No holidays, but smack in the midst of summer vacation when I was growing up. Friends weren't always around for a party - but I'd have it anyway for those who were.
BUT... My first elementary school I attended, the principal also had a summer birthday and remembered watching his classmates celebrate at school and he never got to, so he had a "policy" that any child with a summer birthday was allowed to select another day to celebrate an "unbirthday" at school.

I usually picked my "half-birthday" for my celebration day.