A 20° increase in Arizona (picking Yuma where my father grew up) would mean much worse. The record high is 124° from 1995[1], at 144° and 5-10 minutes of exposure we'd see death[2].
[1] https://en.m.wikipedia.org/wiki/Yuma,_Arizona#Climate [2] https://www.livescience.com/34128-limits-human-survival.html