Hey @ZekeW. The 1st Generation of the Chime and Chime Pro need to to be installed indoors and would not be fit for a garage environment. The 2nd Generation of the Chime and Chime Pro can withstand operating at temperatures 32°F to 113°F (0°C to 45°C). As someone who has been to Arizona myself, it may be a risk still putting the 2nd Generation of Chime or Chime Pro in your garage. Since the garage is not insulated or air conditioned, I know how even on a 100 degree day, it can get hotter when in a closed off, hot area, like the inside of a car or a garage.
Since Arizona can have those more heat intensive days, I recommend getting the device inside when you notice it gets too hot outside. If you notice the device get hot at any time, bringing it inside can help during those times! Lastly, we did vamp up our Chime and Chime Pro for the second generation to be a bit louder, so installing it on the other side of the door of the garage may be a solution for you as well!