I have never been a fan of wearing a helmet...the old cycling cap was fine with me, but I can't seem to find them any longer. I bought a helmet because some clubs require them in my area.

What I have found though is that a helmut protects my bald head from the sun, but allows plenty of air through for cooling. In the winter, I have a black cover that fits over it and it keeps my head warm.

As many times as I have crashed, I've never had a head injury. But, if injury protection is a side benefit to keeping cool, so much the better.