Originally Posted by digger

Why would you feel that you need more protection in winter? I understand that there is a greater chance of falling in winter, but falling can happen anytime. But falling, is falling, whether winter or summer.

Which is what a bicycle helmet is designed for....a fall, that's it.

www.helmets.org

Edit: I should add that the one time I split a helmet in-two was a fall....in winter. I was off-road riding, front tire went through the ice at 20 kph and I did a superman over the handlebars. Landed on my forehead/face, and helmet was split down the middle.