Why Do Cat's Ears Get Hot?

The ears regulate the heat in the cats body, its nothing to worry about.

Cats don't sweat like humans, and one of the ways they get rid of excess heat is through their ears -- they have lots of blood vessels, and when their overly warm blood goes through those, it can lose heat to the air. So probably the cat is warm and just needing to cool off. That said, I'm not a veterinarian. If the cat is acting sick, you might want to get it checked to see if it has a fever.

Well its probly just the temperter in your home or maby your cat has a fever make sure you fell your cats paws to see if there hot that usaly means they have a fever hope that works or if your unsure ask a vet :)

My cats ears get very hot sometimes is this a way of cooling down?

A sign of food allergies, or, if the paw pads are hot, then its a normal way to release body heat.