This heat is going to be a rarity, as usually 90 means 65 plus dew points. It isn’t forecast to get over 50 really in this timeframe and honestly it’s the weather I’d expect in flagstaff az not here.
I would also think there is a rather high fire risk incoming. It’s been dry, and you’re looking at 90 degree temps, 40 degree temps, and a fairly consistent 10mph breeze.