The Raven has a connotation of death, and a bad omen. It also connotates the monotonous tone.
Midnight and December connotate the end (of Lenore's life, and of the narrator's sorrow/dwelling). They also connotate the beginning of something new--the narrator's dealing with the death.
The chamber which the narrator locks himself up in, is just that--a connotation of how trapped he is from dwelling on his sorrow and whatnot.
The tempest further connotates the isolation and entrapment of the narrator.
