This is probably the second year in a row that the cold has become severe in Canada due to unusually high humidity. In previous years the cold was bearable, because people knew how to dress, etc and the air was generally dry. The temperature that our body feels has definitely changed and has brought an epidemic of medical problems not encountered in such profusion in the past. The "new cold" has also been the first subject of conversation this winter as people noticed that they feel the cold much more, even though the recorded temperatures are not by themselves extreme by comparison with other years.
The water molecules conduct heat away from the body and also as water molecules comes in contact with your skin the cold water molecule is takes more energy to heat than an air molecule. If you think about it from a clothing stand point a wool sweater may work well on cold dry day but can be penetrated by water molecules on humid day making it less effective than say a jacket with a water resistant outer barrier.
Find more info here:
http://www.decodedscience.com/why-does-damp-cool-weather-make-it-feel-colder/6736
I am glad Environment Canada has decided to introduce a "humidity factor" for calculating the temperature people feel during the winter.
That is a partial victory. We will see how this new formula is going to work out!