Consider the phrase: The Winters of Quebec are cold.
I understand that the correct form is
Since a possessive form is involved here (the Winters of Quebec), why is
Both sentences are fine. They only have slightly different meaning, and you would use one or the other depending on context, for example:
Ex.1: "Where do you live?" "I live in Quebec" "Winters are cold in Quebec, aren't they?"
(ケベックは冬が寒いですね - "As for Quebec, winters are cold" - The topic is Quebec, something that have came up in the conversation, and the speaker elaborates on that topic suggesting that it has cold winters)
Ex.2: "It's winter now in Quebec" "Winters are cold in Quebec, aren't they?"
(ケベックの冬は寒いですね - "As for Winters of Quebec, they're cold" - The topic is "winters of Quebec", which have just came up in the conversation, and the speaker elaborates on that topic suggesting they're cold)