I grew up in a (New England) world with no air conditioning. I’m not sure how grownups who spent days in offices managed on really hot days–but little kids with backyard sprinklers did just fine.
Keeping our house cool inside needed different tactics.
First, our windows were opened up wide every bedtime, on the theory outdoors would get cooler before we woke up.
Second, once sunrise arrived, grownups stayed alert for the absolute instant when air outside the house got hotter than the air inside. Bang, bang, bang, those windows got shut again!
This morning in Cambridge, MA, I’m sorry to say, that slam-windows moment came at 8:30 a.m. But at least so far I don’t need the whir of my room air-conditioner, thanks to old New England tactics from long ago.