The myth of the *but it's a dry heat* in Arizona is just that. I've lived in the Phoenix metro area for 5 years, and it's anything but comfortable because it's "dry"!!
There's an over-abundance of man-made water holes, aka golf courses, housing developments with "shore-front" homes on man-made lakes of various sizes, as well as the infamous Tempe Town Lake. During the late summer, there's monsoon season---torrential rains, winds, micro-bursts. Don't count on going across southern AZ in the summer, and being comfortable without A/C, or a top on your car.