[wrholt]

It makes sense to wait for a native speaker to chime in, particularly if my analysis is incorrect.

I think you've been distracted by the difference in grammatical number between vacaciones and "holiday". Your concerns would be valid, if the word vacaciones were the subject of the sentence.

However, in my opinion, vacaciones is not the subject of the sentence. The word vacaciones is inside the prepositional phrase de vacaciones, which in turn is functioning as an adjective that modifies the masculine singular noun tipo, which is the head noun of the noun phrase mi tipo favorito de vacaciones. As the head noun, tipo controls gender and number agreement with the adjectives that modify it within the subject noun phrase, and it also controls the gender and number agreement with uno in the predicate es uno con clima frío y mucha nieve.