How much degrees are the temperature in snowstorm?

Today we discuss a new fact which was totally new for me. One of my colleagues told me that in snowstorm the temperature cannot be less than twelve degrees. Of course I have not believed in that fact and began to dispute.
Actually I was in wrong position, my colleagues explain me where is the secret of this. In the snowstorm the water which is on liquid state turned on to hard state as a snow. From the physics we know that when some material change it state from liquid to hard it ray energy. This leads to increasing the temperature in the environment where the snowstorm is. Otherwise when you have an clear sky and cold weather, without snowfall then the temperature decreasing faster with snow melting. The reason is the opposite when the water become from frozen state to liquid stat it absorb hot and the temperature of environment falls.