I lived in Phoenix for a short time, so I understand exactly what you are talking about. Once you hit March, Satan flaps his wings and God flips the oven on Pre-heat. Particularly in the valley.
Not to get too graphic, but I had to switch my 100% Cotton underwear for that new-fangled sweat wicking stuff. Made a huge difference.
At the time I carried a Glock 27 which was pretty easy to conceal under a t-shirt. It was so easy to conceal, in fact that when I switched to that good old Parabellum round, I decided to go a size up. Instead of trucking 9 rounds, I've got 16 heh heh heh.
Go to the love-in thread. I've got a question for you more related to that subject matter.
Before I met my wife I carried open . I had a ccw permit . I rarely carried concealed though. Not much need for a jacket in Phoenix so concealed caring is a bit of a pain for most pistols. Only thing I messed with was the ammo . Normally it was alternating black talons and full jacket rounds . I do still take a day out every month and go to the range and squeeze off 100 or so rounds .
Blesdings
Bill