It really depends where I'm at. For instance, when I lived in Phoenix, I didn't consider it hot until well over 100F. But now in the Colorado Rocks, I'm uncomfortable once it's above 85F.
The sun here at 8,700 feet can really do a number on you. That's coming from someone that lived in Phoenix for over 15 years. Granted in Phoenix I had a/c almost everywhere I went, while here we don't have a/c.
Yes, definitely need the A/C here! You can about fry eggs out in the driveway!