First time mom
The behavior is totally normal, it is how chickens cool off. They pant just like a dog, or cat. By spreading their wings it allows more air to get around their body and cool them off. I might wait until you get the air flow improved a little bit if you're expecting it to get much hotter, and when you do move them into the coop you can put frozen ice jugs in the coop for them to get against to help stay cool. Good luck with raising your NH chicks.