Where did all this heat and humidity come from? Yeah, it happens every summer and although you could just go somewhere cooler like your house, in a shop, or a restaurant to get out of the mugginess, consider a visit to literally a great place to cool off, Mammoth Cave.

How cool is it? Here's the official answer from nps.gov:

How cold or hot can it get inside Mammoth Cave?
Temperatures inside the cave vary somewhat, but usually hover around 54° Fahrenheit, year-round. In the "variable temperature zones" close to the entrances, wind chills in winter can dip below freezing, or temperatures can rise to around 60°.

60 degrees is the "hottest" it can get close to the entrances, 60! which is a lot better than 90 or 100 with humidity.

Find more information on fees, which are reasonable depending on what tour you want to do and and the types of tours available, go HERE.