I wrote an article about winter cycling last year on my website, it's Perth-oriented but most rules still apply (especially
rule #5).
Check it out:
http://www.velophile.com.au/2012/06/25/ ... commuting/" onclick="window.open(this.href);return false;
For temps below ~10 degrees C, I'd recommend a wool cycle cap:
http://www.walzcaps.com/caps_wool.html" onclick="window.open(this.href);return false;
I own a couple of moisture wicking caps from Walz and they are awesome. Have a cotton cap and also a wool cap with ear flaps en-route which I'll test and post a review on my website once done.
What else..
Fenders/mudguards essential to keep yourself and your components clean/dry
Good quality, bright lights (plus a spare blinky for extra safety)
Water resistant jacket (don't skimp too much here)
Merino wool jersey base layer all winter
3/4 or full winter tights for those cold days, keep those knees covered and warm!
Waterproof covers for your shoes (less important if you have mudguards though)
Thick full finger gloves (I use a pair of merino wool gloves as an inner layer and an old pair of MTB gloves over the top for durability/extra warmth on cold mornings)
All that stuff can be bought pretty cheap online.
Ground Effect aren't exactly cheap, but they are good.. check them out (especially the jackets):
http://www.groundeffect.co.nz/" onclick="window.open(this.href);return false;