Heat Tolerance

[Bluetree]

Is one's tolerance for hot weather a genetic propensity or a learned trait?
I have some races coming up this summer in the desert and I do NOT want to deal with the heat at all.

I wonder how much of it comes from my environment. Sure, I live in California, but I live at the beach where it rarely gets above 80°F in the summer or below 45°F in the winter. Most days (year around) the high is 60-70°F. Plus, because of my work schedule, I'm usually out and back before 8am before it gets even "warmish".

But even when I was a kid, I had trouble dealing with heat. I'd be prone to heat exhaustion when all my friends were just fine. I'd get lightheaded and flushed easily. I couldn't (and still can't) sit/stand in the sun for too long without my heart rate shooting up.

I'm wondering if heat tolerance is something that can be learned... I don't want to pass out in the middle of a race! How do you Texas and Aussie gals do it????