I read on a ferret website that a good way to keep ferrets cool is to
freeze a plastic bottle of water, put it in a pillowcase and tie a knot
so the fuzzies can't chew on the plastic.  Put it wherever the ferret
hangs out and don't have a fan blowing on it.  The air surrounding the
bottle will be cool.  If the ferret is hot, he or she can sit as close
to it as he/she wants.
 
Another fun summer activity I discovered myself is to put some water in a
bowl with a few ice cubes.  I put the bowl in the bathtub along with the
ferret so that water doesn't get all over the place.  Rocky loves to dive
for ice cubes, then chew on them.  When he was a baby he chased them all
over the floor, and then put the cubes in his hidey hole--ha ha!
 
Hope this helps.
 
Sharon & Rocky the cool ferret
[Posted in FML issue 3833]