How hot is too hot?

Morning ladies! There was a post on here a few weeks ago that got me thinking - how hot is too hot for an outdoor ceremony? We're in Arizona where the humidity isn't a problem, but I'm afraid living here for the last few years has made me more tolerant to heat and less tolerant to cold. We have an air conditioned space where we can move everything if we wake up in the middle of a heat wave, but just wanted to get some ideas where people who aren't used to the AZ heat are comfortable.