As most everyone have recommended, the D.N.A. is "cool" and does a great job, I agree!
In addition, I'm also in the high desert of L.A. county area. It is a vast dry desert area, much like Las Vegas area and could be the same as what you've mentioned. I have been playing in DNAs' since January and we have had some heat waves since that has gotten up in the 90s-- but it's only almost middle of May. While those temps aren't peak, I'm sure the DNA will hold up to a much higher temp.
Playing 36 holes a day is a piece of cake for the comfort the DNA has to offer in the heat. It has many other featured benefits other than its cool style and comfort. They are light and are great for walking if you're up to that. They are also a very well made golf shoes- it exudes durability, and not to mention it has a stable sole which is great for balance and action. You'll also love the grip in its spikes!
You'll need to try them on to know how nice a golf shoe pair you'll be owning.
Welcome to the FJC! We'd be interested to see which color combination you'll be in.