How can i keep my cats cool?

i have to keep my cats in the shed in my backyard over the summer,does anybody know of any way that i can keep them from getting to hot in there?the temp where i live is about 80 to 95. i have a fan set up and i have ice cubes in they're water but i don't think that that will keep them cool.and yes i know its stupid to keep them in a shed but it will only be for a couple of weeks and i cannot keep them inside cause my dogs will kill them... please help me