craig i also live in Phx.Az. and go up on the rim to camp around august and september..when the sun starts to go down and it really cools off i put on my wooly hat,light poly-pro shirt with a warm fleece zip top..also i always wear wool socks on my feet along with good boots..i wear shorts all the time but i do'nt worry about cold legs as i can warm them around the campfire or if no campfire i get in my warm sleep sack..vince g. 11b inf...