The Monsoon has come so the temps have moderated and the humidity has risen form 5-9% to 35-45%. The will usually go away by the middle of September and humidity will start dropping again..

It's hard to give yo an answer as the weather from year to year (at least in my 25 years here) is so variable. The end of September on can be wonderfull or can be a bit hot. But the really bad stuff is just now on the way out.

It's so pretty out in Scottsdale you will love it no matter when you arrive, but latter in the year it just get better and better. June thru Aug are the bad months add a 1/2 month on each end for acceptable and 8 months of wondeful. So enjoy your trip.