It is impossible to give a full explanation of color "seasons" here so please read the article Color Seasons.
Winter colors are the most difficult to describe. Most neutrals especially the purest grays and silvers are winter colors but then there are some very bright and vivid reds and greens that are winter colors. Winter colors are the darkest colors of all the seasons. They also tend to be very pure colors although the purest winter colors are the purest neutral grays and silvers. Winter colors tend to be pure and silvery but then again, there are shades of gold that are winter colors and the winter reds and greens are almost but not quite warm.