Tourist Town Advice?

I'm 18, currently in high school, and I'm planning to go away to university in the fall. I've been a barista since September in a tourist town near a very popular skiing/snowboarding mountain. We're in dead season so my hours have been cut back and I frequently get sent home early. On top of that, someone hired a new person and we also got a transfer. I'm assuming my store will be just as dead during the summer. I was planning to leave at the end of August but I'm not sure if I should leave now and being searching for a fulltime summer job. Advice?