The setting of Ethan Frome is New England, specifically the town of Starkfield, Massachusetts. While the town is fictional, the description that accompanies it very much resembles a traditional town of that area, specifically at the end of the 1800s. As a town going through changes, and in light of the impact of the modernization that came at the onset of the 20th century, Starkfield is salient for the little effect that this otherwise “worldwide” trend has on it.
Like the name implies, the town is indeed “stark,” that is, plain, unadorned; just not “special.” Added to this are the seemingly perennial coldness that prevented good crops and the long winters that froze whatever had been able to germinate.
The symbolism of Starkfield winters is also that, in the eyes of the narrator, they were bad enough to make life miserable with not much effort. In the case of Ethan, his already unhappy existence—combined with the depressive isolation that long winters often bring—did nothing short of breaking any positive characteristic that could have surfaced from his personality.
Evidence of this can be found in the prologue, where the narrator says:
I [...] felt that he lived in a depth of moral isolation too remote for casual access, [...] his loneliness was not merely the result of his personal plight, tragic as I guessed that to be, but had in it, [...] the profound accumulated cold of many Starkfield winters.
Winter also symbolizes and foretells unhappiness. Ethan hastily asked Zeena to marry him during the winter when his mother died. The thought of being alone on his property during those terribly trying months was scary enough for him to make a choice of that nature. Even Ethan concedes this:
He had often thought since that it would not have happened if his mother had died in spring instead of winter
And speaking of “spring,” note the ironic name of the town where things do seem to be going well: Springfield, the place where Zeena goes to treat her seemingly hypochondriacal illnesses. Why is it that nothing works, grows, or happens in Starkfield? This is precisely why: it is meant to symbolize the darker side of everything, as Ethan epitomizes a life gone into darkness for unfortunate circumstances beyond his control.