More can be written on this. There is a FAQ section, "Clothing and climate" with three applicable answers by /u/cecikierk , /u/redsalesperson , and /u/colevintage .

Although having a lot of FAQ Finders links in one post is not as good, I think you'd like to know about heat adaptations that aren't just the clothing being worn.

'How did laborers in the American South "beat the heat" before the invention of air conditioning?' : Georgy_K_Zhukov on architecture, day schedules, activities, and pointing to a reply by sunagainstgold on French architecture and travel.

"How didnt people kill their self before air conditioning?" : The_Alaskan mentions travel in the last paragraph (the other points, while good, are pretty much covered in other replies).

"Westerns usually show people wearing long underwear and heavy clothes (long sleeved shirts, vests, jackets), even in the sun. Is this accurate? Wouldn't they be hot?" : merryprankster2 on clothing etiquette.

"Approximately how long would it take a middle-class woman to get ready (from waking to stepping out in public) in 1750? How long would it take a middle-class man?" : colevintage on underclothing.

This is not to discourage discussion (indeed, one consolidated set of posts to put into the FAQ would be great). More questions, data, and debate are welcome.