I've found the opposite is true. I am perfectly able to adapt to any level of heat by wearing less clothing and doing less work—warmer weather is dealt with by doing less.
Cold weather, on the other hand, requires work. You have to spend twenty minutes getting dressed in the morning and you can't just sit down to try and warm up. No, you need to do work to maintain you core temperature.
Besides, how hot can it get? Even five degrees above body temperature is considered a heat wave just about everywhere, and it never really gets hotter than that in most places. On the other hand, low temps can easily get to 50 or even 100 degrees below body temperature. Screw that!
I'm also from Miami I can tell you it's miserable in the summer when you're working, but when you're at the beach, staring at topless women in dental-floss thongs, you're thankful for the heat.