That is related to the breed of the chicken, not where it is hatched. A leghorn, or other Mediterranean breed will be more heat tolerant than something like an Australorp. Being Mediterranean breeds they generally will also be more aggressive to the other birds.
That being said, I live in a cold winter climate and any heat hearty birds I've had did fine in the sub zero F temps. And the not heat hearty birds have been OK with the summer humid 90's we get.
I got my first 12 from Ideal, everything from heat hearty Anconas and Cubalayas to not heat hearty Black Australorps. They all did fine here.