Robertsubnet: I hear that!! In 1984, I competed for two days, 5 events each day, in Phoenix, in August. Pretty sure it was the 12-13th. Actually, it was Sun Devil Stadium, Tempe . Only shade was the walkway within the stadium. At 7:00 am each day it was over 90*, with the temp hitting close to 112* early afternoon.
I quarantee, anyone that says " yeah, but it's a dry heat " hasn't experienced it in working conditions. I could not believe how hot it gets out there that early in the morning. Good luck with your prep.