Living in Phoenix I have to add my share. PHX is probably one of the hottest places in the US that an airplane could serve. We get well over 100 degrees, up to 120 rarely. Commercial jetliners are only certified to take off in under 120 degree conditions due to the thickness of the air. In winter since the air is colder it is more dense than hot air, so if we hit 120+ our airport gets shut down as a safety regulation. Since the air is so thin in hot weather, the airplanes have trouble climbing and could stall if the conditions are right. A few years ago we did have to shut down the airport, and being the busiest 2 runway airport in the US at that time you can imagine what a mess that caused!
BMW - The Ultimate Driving Machine