If your cat is a long-hair, taking her in to get shaved is a good idea. When cats get uncomfortably hot, they will seek cool tiles to lay on. They will start to pant to help draw off the heat their body collects. Unlike humans, who sweat almost through every pore, the only way a cat can sweat is through it's pads or by breathing.
If kitty is sluggish and you call her name and she does not respond, that is a sign or impending heat stroke. Other more serious signs are the tongue and gums get bright red and the mouth gets very dry. There will be vomitting and diarrhea. If you see these signs, call your vet and while transporting kitty, cover her with wet paper towels and see if she will take some ice chips in her mouth. But serious heat stroke can lead to kidney problems, bleeding disorders of the brain, and even brain damage.
Provide you kitty with cool, fresh water during these heat waves, keep her indoors or if she goes in and out, make sure there is shade outside, or don't let her out. I bought one of those misting fans for my horse, and also have one upstairs in the cat room, that helps to draw off the hot air when it gets so hot. Today, it is supposed to be 91 degrees here.This will be the first time it has gotten that hot this year.