I’ve had this chart on my computer desktop for a few years. It is a little deceiving. Last year, for example, we saw 120 degrees in June. Two years ago, two of my trees died in one day because it got too hot. They had green leaves all over on one day, and were brown and bare the next day.
This year (2019) has been moderate. As of the end of the first week of June there were only one or two days above 100 so far this year, and then only 100 or 101. We have 110 degrees forecast next week.
Having lived here three years, I must say that it is surprising how tolerable the heat really is. You can sit out side in the sun in the high 90’s and not be miserable. When there is a breeze, and your body’s air conditioner kicks in, it is quite tolerable, but not what I would call pleasant.
If you are not from Phoenix, my recommendation would be not to plan an extended visit from early June until late September. But, by the end of October, and most of the way through May, the weather here is superb.