St. Petersburg typifies small-town America in the nineteenth century. Tom reaches maturity over the course of the novel in realizing that he must act as a responsible member of this community rather than rebelling against its conventions. While Twain depicts the village as an ultimately benevolent support system for its members, he also uses satire to point out the hypocrisies and weaknesses of its attitudes and institutions.
Tom, Huck, and Joe Harper escape to Jackson's Island to live as outlaws, leaving behind the rules and strictures of St. Petersburg society. Its physical isolation brings them all the freedom they could hope for. Yet Joe and Tom they find that they are not happy—they miss the social attachments and responsibilities to others that define their lives in the village.
Finding treasure is a fanciful notion appropriate to Tom's romantic boyhood imagination. Yet this unrealistic dream nonetheless comes true by the novel's end. Tom and Huck achieve maturity with the windfall of their treasure, which heralds the onset of their adulthood in the eyes of society, for they have achieved wealth and status.
In the harrowing experience of surviving several days lost in MacDougal's Cave, Tom's proves his manhood. Like the island, the cave involves physical isolation from the village community. While Tom runs away to the island with dreams of personal glory as an outlaw, in the cave he acts wisely and resourcefully as Becky's male protector. Twain describes the experience in a realistic, unromantic style that speaks for the seriousness required of the adult behaviors Tom performs in rescuing Becky.
Incidences of bad weather occur several times in the novel, each time signifying that Tom is in a particularly troubled psychological state. On Jackson's Island the homesick boys survive a storm that wreaks considerable damage on their ill-prepared campsite. When Becky is away for the summer and his friends are swept up in religious revivalism, a lonely Tom hides under his sheets during a storm that he imagines is meant to destroy him.