It was about five degrees when I left the house this morning around 5:30. It was about two hours before daylight and generally the coldest part of the day. Was I cold as I rode through the dark dark world? No.
Winter biking is not as hard as you'd think. I often tell people that I'm warmer properly dressed on my bike than they are sitting in a cold car waiting for it to warm up. I have different levels of layers that I use for different extremities of cold. Here's my basic gear:
The thin polar fleece hat works great under my helmet and makes sure my head and ears are warm. Hands are especially vulnerable because they're out front on the handlebars and can have a lot of wind chill factor. I use a pair of fleece mittens with finger flaps over a pair of unlined buckskin gloves. The two layers are enough to stop the wind and it's nice to have the glove-like feature for U-locking and other fine finger work. I wear a fleece vest most of the time during the winter and that zips up around my neck pretty well.
On extreme days like today I add extra thick socks, long underwear, and a balaclava to cover my face.
Road conditions are the only thing that consistently stop me. Usually the roads stay pretty good in the city because of snow emergency plowing. Unfortunately, this year we acquired a layer of ice under the snow on side streets that the plows can't do much about. I like to take mostly side streets, so I had to change my route to the dry main roads for now. I hope that the warm spell we're supposed to have in a few days will melt that slippery under layer from my favorite streets.
Honestly, one of the best things about winter biking is the looks of respect and unbelief people give you about it. I often hear, "You're a hearty soul." Maybe I am and maybe not, but I don't think most people know how easy this really is.