The West Wind moves about as an "unseen presence" throughout autumn, creating a powerful change that ushers in winter. The speaker observes that the West Wind is both "destroyer and preserver" to the earth, inflicting a temporary death so that life can eventually continue in the spring.
The Atlantic Ocean's "level" and smooth surface is transformed into enormous waves by the West Wind, and this same wind also awakens the drowsy Mediterranean Sea from its summer of lethargic slumber. The winds of autumn transform every part of nature, creating "rain and lightning," "hail," and "storms" that usher in the bleak season of winter.
Since the West Wind is called the "breath of Autumn's being," it stands to reason that it is seasonal and must disappear at the end of fall. Where, then, does it go? In lines 5–8, we are given a clue about where this place of slumber might be located:
Who chariotest to their dark wintry bed
The winged seeds, where they lie cold and low,
Each like a corpse within its grave, until
Thine Azure sister of the Spring shall blow.
The West Wind is the "chariot" of the seeds, transporting them to their temporary "graves" below the earth's surface. Since the wind has acted as the vehicle for these seeds, readers can infer that perhaps the wind itself rests here with these dormant seeds; as the next autumn approaches, the West Wind will once again awaken to drive the dead leaves from the trees and begin the earth's process of renewal all over again.