Shelley's poem is divided into five sections. The structure here is the following.
- The appeal—the poet asks the West Wind to hear his request.
- An expression of the poet's condition—the poet fears his poetry has grown ineffective.
- Finally, a request—the poet asks the West Wind to adopt him as its "lyre," or voice.
To describe the poem in a bit more detail, the first three sections are an appeal to the West Wind to hear the words of the poet. This is a well-known trope in classical poetry, and it allows Shelley an opportunity to engage in some description of the West Wind, which he calls both "destroyer and preserver." The wind drives the dead leaves before it, and "chariotest" (drives in a chariot) the "winged seeds" into the ground, paving the way for renewal in the spring.
In the second section, the power of the West Wind over the clouds and weather is described. The clouds are the "bright hair" of a "fierce Maenad," or of an approaching storm. A maenad, in classical literature, was a female follower of Dionysus, the god of wine, fertility, and festivity. The maenads were often portrayed as being in a state of ecstatic frenzy, so Shelley's point is to suggest that the West Wind is akin to the wild spirit of Dionysus, singing a dirge (lament) for the dying year.
In the third section, the West Wind is described as waking the Mediterranean Sea from its summer rest "in Baiae's bay" or "cleaving chasms" in the Atlantic, causing the "sapless foliage" in the ocean to "grow gray with fear." The Baiae is a reference to a place near Naples that was a well-known Roman resort; the "old palaces" are a reference to the Roman villas that can still be seen there.
All of this description is a kind of flattery, or an attempt to get the West Wind to pay attention to the poet and his troubles. His trouble, expressed in the fourth section, is time. "A heavy weight of hours" is oppressing him; he is no longer as he was "in boyhood," when he could be the "comrade" of the West Wind and its wanderings over the world.
In section 5, he makes his plea: he asks the West Wind to make him its "lyre" (harp) like the forest, a reference to the beginning of the poem. This can have several meanings. As the West Wind's lyre, Shelley's poetry becomes the "voice," or music, of the West Wind. The reference to Shelley's "leaves" falling like the leaves of the forest is a pun—Shelley's "leaves" are the pages of his poetry. He asks the wind to drive these dead leaves ("dead thoughts") "over the universe" to "quicken a new birth."
This request can be understood in several ways. Shelley feels that his poetry has grown old and stale, and he asks the Wind to inspire him; the "new birth" is the renewed vigor of his art.
Another popular reading is to understand the West Wind as a symbol of popular revolution. Shelley supported the French Revolution but found the radical spirit diminishing in Britain. His appeal here can be understood as an attempt to rededicate his verse to revolutionary ends. The "spring" that follows winter in the final line is both an artistic and political rebirth.