Heat or humidity?

It's both temp and humidity. And, since we mentioned AC it's important not to vastly oversize AC units. What can happen is that the AC will be so big that it will short cycle and force the temperature down before the AC removes much humidity. The result can be a cold clammy feel in the house..........cold and wet. A smaller unit runs longer, and dehumidifies much more before really having an effect on the temperature.

I grew up in this part of the country, and we never "thought" of needing AC in our house and had none in any of the cars until just before I joined the Navy in 68--Dad bought a 66 Ponch I think Bonneville. It was used, he would not have "looked for" AC it just happened to be equipped.