Our air conditioner stopped working recently, and it’s about 80 degrees in the house. I’m not worried about myself or my husband, but I do have two cats. How hot is too hot for them to be in the house? Someone once told me about 85 degrees F, but he didn’t seem too sure.
80 or 85 degrees doesn’t seem particularly warm. I’ve seen cats fall asleep on hot air registers (typically 100+ degrees) and next to wood stoves. Once the temperatures hit the 90’s, you’ll probably see the cats get less active and maybe eat less. If you have a cellar, you might consider letting them roam downstairs where it’s cooler.
Hmmm, I don’t use air conditioning until it hits 97 or so and my cats have always been fine. Is 85 reallly considered hot? I think as long as they have access to plenty of water, they’ll be fine. Weren’t cats originally desert creatures anyway?
Well, the ancient Egyptians weren’t known for their air-conditioning, but they *were * known for their veneration of cats. I don’t think you need to worry much. Cats usually just become more nocturnal whan the temperatures rise. You may have to deal with a hyper cat around 2am, but 80+ degrees won’t hurt them. 
They seem to do just fine in Australia.
I’m not sure if 85 is considered particularly hot. At least I don’t really consider it that hot. The reason I wanted confirmation was because that number was given to me by someone at the Humane Society. Given, that person was a volunteer, but they were the only person available at the time to answer the phone when I called.
Anyway, 85 degrees seemed a little cool for a cat to overheat since, as you and silenus have noted, domestic cats are descended from a desert cat.
I’m sure they’ll be fine. Thanks for making me feel better!
Yes, they are, but the also venerated dogs, cows, and other useful animals. Why do people only remember cats? 
In any case, housecats evolved from desert animals. They can instinctively handle the heat.
I’m from Australia and had cats all my life. I found during the hot summer months which were often over 100 deg for days on end, they preferred to lie around outside rather than be inside where it was air conditioned. In fact they refused to stay in the air conditioned rooms at all so I’m sure they’ll be fine in 80+ temperatures. As has already been mentioned, make sure they have plenty of cool water available.
Don’t cats have ridiculously high average body temperatures, like in the 105F range?
Shouldn’t that make them able to tolerate more heat than us, or am I thinking backwards?
This is of particular interest to me because I live in Arizona and I just got a kitten (pics here :D)
On a TV show about cats, they show one lazily lounging by a blacksmith’s furnace where a thermometer showed an unbelievably high temperature (about 150, I think). The answer is their fur. Very, very insulating. Both ways.
Remember, when a cat lies in your lap, it’s showing you all the affection it would to a radiator.
Peace.
Medium rare is about 145, and they start to get really tough around 160.