Ironically, I don't find that I get as cold when I'm riding in rainy 40 degree temps vs dry 40 degrees.
Silver, layer up and get out there. How can you acclimate if you are in your house, off the bike? Every day that the pavement is clear of snow/ice/slush/snow-debris is a gift this time of year and remember, we still have several months before the threat of snow/ice is over. If you get out there and it's unbearable, you can turn around and go home. I'm betting that you find it invigorating.
The hardest part is getting out the door. Usually when I dread riding on a cold day, I get five miles into the ride and realize that it isn't as bad as I anticipated.
Here's a treat---go out after dark and see all the houses decked out with Christmas lights!