Poe creates a somber melancholy mood that morphs into a deep sense of foreboding and finally transforms into terror as the poem continues.
In the opening of the poem, Poe sets the stage which adds to the somber effect. The time is described as "midnight dreary", giving the distinct impression of darkness. The atmosphere is enhanced by the "bleak December" setting, hinting at a cold darkness. The dying embers of the fire cast visions of shadows and a creeping chill about the room. The setting of the room provides the gloomy somberness for the mood of the poem.
The mood is transformed by Poe beginning in the third stanza. Here he repeats to himself the tapping on his door is nothing but a visitor. The self-assurance connects with the reader's memory of fearful moments. The mood has grown much more somber and foreboding. The poem reaches the pinnacle of fear during the interactions with the raven. The protagonist is driven to yelling at the bird, imploring for a name. The crescendo of the poem is reached when he calls it a "thing of evil," "bird or fiend" and shrieks at it to leave him alone. Poe paints a picture of a man driven mad with fear.