I rode down to -20° last winter. Merino wool baselayer, really warm mittens, wool socks, wool sweater, insulated boots, down jacket (or down sweater and shell if above 0°), ski goggles, merino beanie under my helmet, merino buff, and plenty of kleenex in my pockets. I have studded snow tires. I found that I enjoy winter commuting more than summer commuting. Heat is more likely to make me wimp out than cold.

Deb