As a Colorado based company, we have some of the best weather when it comes to winter months. So installing a new roof during the winter is really not a problem and we do it all the time. Some things to consider when planning out the job is going to the weather forecast and temperature. We can install asphalt shingles as long as the temperature is above 40 degrees. Under 40 degrees, they become brittle and can crack or break during the installation process.
Also note that when contacting a quality roofing company when you see a leak after a snow fall that they will not be able to inspect the roof until all the snow and ice have melted off to look for the cause of the leak. It is very dangerous to get on a wet or icy roof.