You should turn your furnace on before the cold strikes to make sure that it is working right. There is nothing worse than finding out that there is a problem after your house is already freezing cold. If you already checked your furnace or even if you forgot to check it  and your furnace still goes out, you will have to call a furnace repair man. You can look online for Furnace Repair Mn or you can check your yellow pages.  Better yet, if you know someone than can give a positive recommendation of someone that they have used, I would go with them.