Make sure your shirts and long pants are loose fitting. You will need 2 or 3 sets. A belt will hold your pants or shorts up and hold your hammer holster. A good place to shop is your local Salvation Army or GoodWill retail shop. A lightweight hat or cap, with brim.
Sunburn is a major problem among flatlanders out west.
Bring two bandanas - good for wiping your face in the heat of Prescott, as a scarf or headband, and to blow your nose. Problem with cotton sweaters is that if they get wet - you get cold. You may also be able to rent one from the university union or camping club on campus. Sleeping bag, medium weight. These are often called 3 season bags.