Knowledge: During winter, green and red colors are popular as it fits to the Christmas mood. On the other hand, black is the most loved shade to hair dye during the cold season.

Conversation:
I'm thinking about coloring my hair soon, any tips?
I don't know of any tips. People usually color their hair to cover gray, to look more fashionable, or to restore original hair color.
I see. Then do you know which color is popular during winter?

Response: Ah yeah, black is the popular color to hair dye during winter.