The main thing is to keep yourself safe from frostbite. I am working out in the open here in new york and it has been cold.It has been under 10 deg. f. We recently sold our house and my shop to buy a new house. It sold faster than we thought and winter hit before I could build the new shop. I sell alot of firewood pokers and other ornimental items in the winter time.
First thing is to make sure you have the right gear to keep your body protected if you are going to be working in this kind of weather. Dont push it when you start to get cold go inside and warm up. I would invest in good cold weather clothes (carharts, insulated underwear, hats, gloves ect.). If you dont already have this stuff. Your young and have alot of time to be forging. Dont push it be safe and have fun.