What to do when it's soooo hot outside??

It's June 5th today and it's a scorcher!! We were supposed to hit 93 at noon today and we easily reached our target. The sun is so, so strong and bright, barely a cloud for coverage. Our afternoon thunderstorms haven't really begun yet, as the humidity hasn't really set in yet (oh, more to look forward to!!). This is when Floridians start to hide inside, taking shelter in the a/c. It's only June, and I'm already running out of things to do with Katelyn. We spend a lot of time in Barnes and Noble (great kids section and they have a train table for the kids...and a Starbucks for the moms), Chuck E. Cheeses (but gets v. crowded by 10:30am), Library, soon there will be summer movies at 10am once a week for the kids, and summer school starts in two weeks (2x a week). We also alternate houses for playdates. I need more ideas!! Please help! What do you do up north in the winter to keep the kids entertained? We have 4 more months of this intense heat. I know we'll be hanging out at home more when the baby arrives, but until then , we both like to be busy and out and about. Any ideas you can share are appreciated!!