Here in Arizona , you have to be VERY careful , the sun is so intense and low humidity , that skin cancer , sunburn , and dehydration are big issues . Sun block out here is not a frivolous thing to keep . Unfortunately , if you live in this region , skin cancer is something you have a chance of getting if you are in the sun frequently . I have had a skin cancer removed , and know several others as well . The desert will kick your ass if you dont pay attention to what you are doing in it .Travel at night ? Bad idea ! you want to see what the terrain has in it ( rattlesnakes dont sleep at night btw , everything they eat is more active at night ) . Lot of nasty things in the desert you want to be able to see , and depending on what part of the state your in , many hazards left over from the old west , like vertical mine shafts .