Ive been wondering the same thing, I live in phoneix AZ and i will also be keeping them in the garage but i have been doing some tests, in my appartment our AC went out and it was around 100 in the appartment but i had a fan going on them and they seemed just fine, i just built a rat rack and i put little computer fans on each tub that will run none stop, im still testing it making sure there are no fires ext, but ill let you know when i move into the house and put the rats in there new home.