Can you help me?

Well I think the Orpington is the best bird to have, It gets close to 100deg. here in NC. & tonight it is about 16deg. & once you get your hands on them they calm down verry good, good luck.

 

Between Barnevelder and Austalorp, I would definitely choose the Australorp. They are very excellent producers and are friendly. Most importantly in your area is that they are cold AND hot hardy so they do good in almost any condition. Here is a hatchery they has charts for each breed of bird. Example: type in Australorp in the search box, click on the correct breed, scroll down and look at the hardiness, egg quality, producing, docile or aggressive, etc.

 

Our Australorp is probably the most friendly and also confident hen in our flock - she has chased off our Boston Terrier when it was trying to harass the chickens. According to what I read they are supposed to be heat tolerant which doesn't make any sense to me being large and black. If it doesn't get terribly hot, our Red Star is the most productive and docile hen of our flock. She isn't much for cuddling but she isn't flighty either.

Leghorns would be good in heat I imagine.