Altitude is everything. Flagstaff, at 7,000 ft. ASL averages 11" of snow in December. Phoenix at 1100 ft. and 140 miles south, gets a dusting at most. I worked with a guy that went to college in Flagstaff. He and his buddies hopped in a car and drove to Phoenix on weekends, rented a motel room and hung around the pool until Monday.