Bah, you people are pussies. I was recently on vacation in Death Valley California, where temperatures were above 50C, and I have my 14 month old son with me.
This is the kind of heat that when you step out of your car, you *literally* feel like someone put a hair dryer on your eye socket. I kid you not, Death Valley is very windy, and I felt like somehow had a hot hair dryer blowing into my eyes.
And yes, Death Valley is about hiking. Of course, I didn't do much of it with my son. I kept him outside for no more than 10 minutes at a time.