Our Pyrenees do fine outside in any season. During the summer they go to the creek to stay cool during the day and stay on guard all night. We're in East Texas, about 30 miles north of Tyler.
We don't subscribe to the belief that they can't be pets, we love 'em and they still do their job. They're not overly comfortable in the house, they spend most of their time outside when they are all grown up. I do like to keep puppies close and socialize them with us, but at about 6 months they are ready to be out all night and run with the big dogs.
Right now we have Beorn and Eleanor (the adults) and my puppy Lily from Eleanor's last litter. Lily was the runt, suffered insecticide poisoning, was run over by my van which dislocated her sacroiliac on both sides and then came down with (possibly) Parvo even after 2 vaccines - all before she was 4 months old - and she's a trouper. She's been staying out with her Dad at nights while Mom is in here with the latest litter of pups.
My husband raises peafowl and we have a few chickens and Call ducks, and we wouldn't be without a Pyrenees here. Nadine (Moodene) has one of Eleanor's named Babe, she's a beautiful dog.