Here is the deal on animal's coats. An animal starts growing a winter coat based on the amount (hours) of daylight during a day. Hence, the farther north, the less daylight you have. It is not based on the temps outside. If you want to shed your dog off, put him in a house with a light bulb on all the time. His body thinks the sun is out, and the hair will slip. It works with horses, that's how they get those slick summer looking coats in the middle of the winter. It is also how you end up with a sick show horse.
Dogs don't feel cold the same way that humans feel cold. Dogs don't have the vaso-constriction muscles like us. They don't get cold feet, or cold ears. When they get cold, they get cold all over. If a dog has adequate protection, from cold winds, adequate food and water, and a place to run. There is no reason why a dog can't stay outside during the winter. You will probably find that a dog that winters outside to be healthier than a dog that stays inside all the time.