An average of 120 degrees F? Definitely too hot to (door) handle! Of all the extremes of weather, I find excessive heat the worst to deal with. You’re stuck with it if the AC can’t cope / doesn’t exist. After all, you can always put more clothes on or turn the heating up when it’s too cold.
I visited Phoenix briefly on holiday a few years ago. We were there in October, and it was still pretty warm! Las Vegas was even worse — we ended up using the walkthroughs between the casinos to keep out of the heat. I can remember at the time wondering what would be like to live there in the height of summer. And now I know!
Iowa sounds like a far more bearable place to be.