We're hard-core mountain bikers... I'd give anything to be able to ride in Arizona (it might be a little bit warmer than it is here - in Dallas - but it's not nearly as humid; I don't care about the temperature anymore, it's the humidity I don't like). We hit the trails in 100+ weather for hours in a row all the time; with the proper gear (and a Camelback!), you'll be fine

That, and R/C cars...