Looks like a rattle snake, triangular head. Cant see a rattle, though.
I had to Google it to find it, but it's a Long-nosed snake and non-poisonous. The shape of the head throw's you off a bit because of that can pull tab on it's neck.
http://www.reptilesofaz.org/Snakes-Subpages/h-r-lecontei.html