Well, how do I know summer has arrived where ever I am? Well, usually by the need to turn on the air conditioner. That has hasn't happened here yet. Oh, wait, there was one day we turned it on because it was 73° and about 95% humidity. We didn't need the house to be any cooler than it was, but I get kind of fussy and cranky when the humidity is that high. The best way of knowing summer is here? Well our anniversery would fall on the "First Day of Summer" so that tends to help.
The whole "School's out" thing helps too, especiall since it now involves people being home from college!