Right, humidity and barometric pressure are also factors.
Like, even when it's hot in a coastal city, the effect of the heat would be somewhat blunted by the humidity and elevation (or lack thereof).
Arizona is dry, so heat compounds the already existing extra travel due to the lack of humidity, but overall it's elevation isn't that big a deal, only 300~ feet above sea level.
Colorado would have compounding factors of elevation, lack of humidity and more heat in the late stages of summer.
Edit*** correct lack of humidity to barometirc pressure. I R stoopid.