My tips for heat waves - When I had a house with a cellar, I would go down and lie on the concrete cellar floor until I got chilled. Like a slab at the morgue, it sucks the heat out of your body.
When upstairs quilting, I would get a wet washcloth and rub it over my bare arms and legs, bonus points if you can sit in front of a fan while you do this. In between uses I would keep it on the back of my neck.
I would much rather bundle up in cold weather than deal with heat.