My answer: I -don't- manage to look chic. At all. It doesn't matter what I'm wearing or how I prepare. My body becomes a greaseball, my hair frizzes up, and my face becomes an oil slick. I have long resigned myself to this fate and have given up all hopes of ever looking sleek and polished. This might be TMI but it seriously bugs me: My hair tends to smell funky and sweaty once it starts to warm up. I don't know why. It happens regardless of the shampoo or product I use. It really bugs me but I haven't found a solution yet.
I'm a princess about air conditioning. I can't live without it. But I hate it when it's turned down to 65, or used when it is under 80 degrees outside. That's just a waste of energy. 72 is my sweet spot, but that is still too warm for most people. But I'd much rather be too cold than too hot for the reasons mentioned above. Both are equally uncomfortable to me, but at least when I'm too cold I can still LOOK nice.
My favorite thing to wear on days like that--and you'll probably hate my answer--is a lightweight sack dress. Virtually all my dresses that I have bought lately are polyester. I have given up on finding natural fibers at my price point--at least exclusively. I do have a few cotton ones though, and I'll be sticking to them on the scorching hot days. My only exception to that rule is the blue UO sack dress because it is so lightweight and doesn't really cling anywhere on my body, so the fact that it is polyester doesn't really have an effect on its breathability.