Is not the title itself a metaphor? Carols at Christmas tell stories about the Baby Jesus, Mary, and Joseph; or, they tell of someone's seeing the star in the heavens, or they relate some other facet of Christmas with lyrical lines that form a narrative. Thus, A Christmas Carol tells the story of Ebenezer Scrooge, his heartlessness and his various experiences which effect a powerful change in the character.
At the end of Dickens's classic tale, Scrooge exudes warmth and kindness, much in contrast to his description in Stave One which is an extended metaphor:
A frosty rime [frost] was on his head, and on his eyebrows, and on his wiry chin. He carried his own low temperature always about with him; he iced his office in the dog-days; and he didn't thaw it one degree at Christmas.
Scrooge is so unfriendly, cold-hearted, and cruel that the very air seems to chill with his presence.