It's a very good point. We have horrid humid summers in Montreal, and had higher temperature than usual these past few days. Most of the frogs I keep don't tolerate high heat, but the Phyllobates terribilis and the Atelopus hoogmoedi even less. So fans were installed in their tanks.
Here's a tip: Make sure that if you install a fan in a tank where high humidity is needed that you increase your misting as stronger air circulation will dry up your tanks faster.