It's your most recognizable dream sign. Recognize it and use it to become lucid.

I almost always have rain or storms in my dreams, sometimes even floods. It doesn't happen that often here though I've seen some amazing storms and floods. They are in nearly all of my dreams, and the really big rains and floods sometimes help me become lucid.

Try and use your dream-snow to spawn lucidity, do a reality check and enjoy the dream.