How can it rain when the temperature is below freezing?
All precipitation starts out as snow high in the atmosphere. Occasionally, as weather systems move over the area, a warm layer of air aloft can move in causing the snow to melt into raindrops as it falls through this layer. At the same time a shallow layer of very cold air with temperatures below freezing can exist over the area. The rain can remain in liquid state as it falls through this shallow, cold layer because it does not have time to freeze. However objects on the ground will be below freezing so when the rain hits them it freezes upon impact.
