@KDOGG331
I forgot where you're from and told you it gets chilly

I'm a dork!
The biggest thing you're going to notice is the dry weather and the sun. I suggest sunblock if you burn easy. Shoot, even if you don't it's a good idea. Given your normal location, you won't be cold, trust me. Despite that, some places put the chiller on frigid so it's possible to get chilly inside. I typically have a light sweater, tank under and I wear capri type pants a lot. You may want sandals too. And lotion. It's very dry here compared to what you're used to.
Have lots of water. Let me repeat...have lots of water. You will be dry and thirsty. Did I mention it's dry here? It is

All joking aside though, have it with you always and drink a lot while you're here.
People are allowed to carry guns here without a permit so don't be surprised if you see people with them on their hips right in the open. I only mention it because my employer brings people here for training and some of them have been wide eyed and a little frightened. It's legal and many here do enjoy exercising their rights.
I really hope you enjoy Phoenix when you visit. It's a pretty neat place with tons to do and you'll be visiting at a nice time of year.