mid 80s...
Dad still hasn't turned on the a/c this year.
That second night...trying to sleep was brutal. I don't know if it's because I've grown used to a warmer house thanks to Dad (old man + heart condition = warmer temps inside the house) or if it was the couple years working at my previous workplace with no a/c or if it's just how I am, but I can tolerate somewhat warmer temperatures inside during the late spring/summer/early fall. I'm used to the a/c being set at 78°, prefer it to be 76° and am actually a little cold when I go somewhere and the a/c is 74° or under. And I don't feel I "need" a/c until it's either been in the 90s a couple days or until it's SUPER humid.
At the start of our trip a couple weekends ago, I told good church friend to set the a/c in the car and in our hotel rooms at whatever SHE was comfortable at...I had both a jacket and a hoodie, so I was ready. And then it barely made it into the 70s on any given day we were in the South.