Phoenix resident here — granted, it gets over 120 a couple times a year, but the average isn’t 120 — more like 105 or so. We get down to low 90's/high 80’s in the wee hours of the morning.
I was here the day we hit 122, back then I was walking to and from work, and the trip home after my shift on that day the soles of my Converse All-Stars were sticking to the sidewalk with each step. I imagine it’s how flies feel when they go trucking over a strip of flypaper.
While I have never seen an egg successfully cooked on the sidewalk, at my work a couple of weeks ago (where we hit 118, I think) they tried cooking a frozen pizza in the parking lot on a sheet of foil. That worked slightly better than cooking it in a microwave. I have, however, had a cookie that was cooked on a dashboard inside a sealed car that you would have sworn came out of a proper oven.
TLDR: average of 120 is a bit high, but it’s damn hot. Best thing to cook in the heat is cookies inside a closed car.