along with tips to keep warm:
If it's going to be really cold and you'll be outside for awhile find some hot hands
http://www.heatmax.com/HotHands/index.htm that's their website and you can probably find them at drugstores, though I'm not sure because we buy ours at Costco in bulk. I have two horses so I spend a lot of time outside in the cold and they work great! There are also feet warmers but those aren't as good.