The tone of "Young Goodman Brown" is formal and somber, particularly in its use of elevated, despairing language and frightening descriptions of nature.
The story begins with a sense of foreboding, as the sun is about to set on Salem, and Goodman Brown is heading out on an unspecified journey that makes his wife afraid. After she begs him to stay, he reflects:
"Poor little Faith!" thought he, for his heart smote him. "What a wretch am I, to leave her on such an errand! She talks of dreams, too. Methought, as she spoke, there was trouble in her face, as if a dream had warned her what work is to be done to- night.
The language in this passage is characteristic of the story's tone, and a few things are worth noting. For one, the archaic words (which would have been outdated even in the 1830s when the story was written) such as "smote" and "methought" give the story an important, weighty quality. These words also evoke biblical language, which is important, since sin and the devil are central to the story. By using a biblical tone to tell a story about the evil lurking in the heart of all people, Hawthorne is borrowing the rhetorical authority of religious texts to give his somber message more weight. Second, this passage is explicitly foreboding, as Goodman Brown is analyzing his wife's dread about his journey, and he comes to think she had a prophetic dream that warned her about his evil intentions. This is one of many clues Hawthorne gives throughout the story that Goodman Brown is headed toward a sinister fate.
The tone becomes somewhat frantic partway through the story, as Goodman Brown begins to realize that his journey into the woods is going to shake his entire worldview by revealing to him the sinful nature of many respectable people in his community. As Goodman Brown tries to keep his faith in God and humanity against all the evidence he's seeing that humankind is evil, the tone of the story reflects Goodman Brown's moral frenzy. This passage encapsulates the tone well:
On he flew, among the black pines, brandishing his staff with frenzied gestures, now giving vent to an inspiration of horrid blasphemy, and now shouting forth such laughter, as set all the echoes of the forest laughing like demons around him. The fiend in his own shape is less hideous, than when he rages in the breast of man. Thus sped the demoniac on his course, until, quivering among the trees, he saw a red light before him.
Finally, once Goodman Brown has lost his faith, the story's tone turns somber and gloomy. The weather grows "chill and damp," and he walks "slowly" through Salem, feeling "bewildered" while acting suspicious of everyone he encounters, including people he used to love. Goodman Brown is left a "stern, a sad, a darkly meditative, a distrustful, if not a desperate man," and his life and death are characterized by "gloom." It's a relentlessly sad ending to a frightening story.