Answer:
A seasonal fashion statement named for the weather it's worn in.
I can be as thin as a picture frame but my insides have many things you can see.
One am I, among six others: Largest, smallest, cold, dark and two brothers
What is it that after you take away the whole, some still remains?
Cycle Cycle Cycle.
Be sure to shout for its answers are weak, but there is no language it cannot speak.