In "The Road Not Taken," what is the season in which the poem is based?
This poem does not directly tell us in which season it is based. Rather, we have to look carefully at the content of the poem to pick up the various clues that there are that suggest a season. If you read the poem carefully, you can infer that the season is probably fall. Note how the wood is described as being "yellow" in the first line of the poem. The road is the second stanza is described as being "grassy," which indicates that we are not in the depths of winter. Lastly, and most tellingly, when the speaker is trying to compare the two roads in the third stanza, he finds little difference between them:
And both that morning equally lay
In leaves no step had trodden black.
The existence of fallen leaves is a very strong indication that the poem is set in fall, as the leaves on the trees were changing colour from their standard green to "yellow" and there are leaves on the ground, covering both paths.
This poem is about a turning point, and the choice of season reflects this. The speaker finds himself in a "yellow wood," where we can assume that the leaves on the trees have begun to turn, but have not yet deepened to brown, nor fallen entirely from the trees. The autumnal season is beginning, but it is in its infancy, with the path still "grassy." Although a big change is coming, it has not yet gone beyond the point of no return.
We know that some "leaves," not yet "trodden back" by any passer by during this season, have fallen onto both the paths that confront the speaker. This signifies that, although the decision has not yet been made and the season is not yet fully underway, a commitment has been made. At this juncture, it is too late to turn back, just as it is too late to reattach the leaves to the trees: a path must be chosen.