Hey! I live in Mississippi and I have 2 yorkies. I keep a puppy cut on mine all of the time simply because it's easier to take care of and they don't get quite as messy outside.
When it comes to keeping them cool outside, mine love the water, therefore I bought them one of the cheap kiddie pools from walmart. It's in the shade in my backyard, so when they do have to stay outside for longer periods of time than just to use the bathroom they have something to stay cool in and it's also a lot of fun for them!