Dry Scalp during the cold weather?  Probably not dandruff...  
The difference between the two:  Dandruff is actually a fungus.  http://en.wikipedia.org/wiki/Dandruff
Dry scalp comes from the cold weather drying your hair out.  
You could also not be washing your hair enough.  During the cold season, everyone's hair, skin and nails dry out.  Moisturize, moisturize, moisturize!  Skin, hair and nails.
Cuticle oil for your nails, Lotions for your skin after showering and for your hair, wash it every other day.