Good Morning!
Having commuted year round for a bit longer then I care to admit, I have gone through a number of clothing systems and have come up with a pretty good routine.
First off, layering is your friend. As is a good trunk bag or panniers to peel off layers when you have misjudged the weather.
I usually start off with bike shorts and a synthetic t shirt.
On top of that I choose multiple layers of synthetic sweat pants and sweat shirts. No need for the expensive stuff, wall mart is a preferred supplier. Its going to get dirty and greasy anyways. I tend to gravitate to the blaze orange sweat shirts for visibility and safety.
Top layer is either a nylon wind shell/pants or a lightweight jacket/wind pants. When it is really cold, I will go for the heavier coat or parka.
For the feet, do not skimp. When you have cold feet you are uncomfortable and will have a lousy ride. I use lightweight wool socks supplemented with heavy wool socks when necessary. Have not tried synthetic socs because I have had so much good experiences with the wool. For cooler weather I use heavy padded athletic shoes. Get a size or two bigger for the heavy socks. In really cold weather, I use boots. Make sure your feet are not squeezed with tight shoes or your feet will get cold. Toe clips get adjusted for the size of the shoes I am using.
For the hands, I use heavy gloves from the discount stores. I also have extra thick grips on my bicycle handlebars, to insulate the hands from the cold aluminum handlebars.
For my head, I either use a lightweight skull cap under my helmet when cool. When it is freezing or below, I use a snowboard helmet, sometimes with the skull cap. I tape over the vents in the snow board helmet.
When it gets below 10 degrees, I usually drive to work in my truck although I have commuted in below zero weather but need to get mentally prepared for it. Parka's, shoe pack boots, and face wraps are required in those conditions as are tires with a healthy tread.
I usually carry extra skull cap, gloves, and socks for the return trip.
Good luck and let me know how you do!
Sincerely,
Cranky