Symbolism, Imagery, Allegory
Chapter 13 is all about Tom's scary three-mile walk home from the mill, in the dark, in a raging snowstorm. The snow is a little nod to the regionalism thing going on in the book. With an average of 190+ inches of snow each year, Boonville is ranked the sixth snowiest spot in the U.S. and has proclaimed itself to be the "Snow Capital of the East."
So the snow is a symbol of Boonville, but it's more than that, too. Tom's trek through the snowstorm is a symbol of the power of determination and self-reliance.
In the storm, there is the very real threat that Tom could get stuck and freeze to death; he's even heard stories about that kind of thing happening. In addition to being afraid, Tom is also mad and frustrated:
He couldn't see a drift until he got into it and started floundering through, which made it hard to hold the [Christmas] packages safe up under his coat. Each time it happened he became more upset and angry. He wanted to punish the drift, kick it, hurt it some way, but there wasn't any way to hurt snow unless maybe by melting it. The notion of having to melt his way all the way from town to home was absurd enough to almost start him laughing. He felt better, and for a while it was easier to plow ahead. (13.8)
Kicking snowdrifts is about as futile as it gets. But it shows that, even though he's angry and scared and having weird urges to punish the snow, Tom realizes that it's impossible—even absurd—to change the weather. All he can do is rely on his knowledge and skill to get him home safely.
That gets us thinking about the overall meaning of the novel. Tom is saddled with some tough life circumstances, but he can't change them, just like he can't melt the snow. However, he can use his skills to get himself out of the bad conditions. It's a lesson in good old self-reliance. Don't get upset, work your tail off, and eventually things will get better.