wind, the speaker describes, comes from the old hills in the land where "tired" hearts such as his reside. He imagines the country as being cool and filled with birdsong and a place where those who have been tired and weary can find rest.

The speaker imagines a voice in the west lands calling to him, telling him that it is April, time for blossoms and bright sun and warm rain. The voice appeals to the speaker to return home.

It encourages him to do this by telling him that the corn is green and the skies are blue and that if he comes home to see the bees and the "merry spring," he will be able to rest his feet and take advantage of the world which is like a "balm" for those who have been emotionally bruised.

The speaker puts these words into the proverbial mouth of the west wind, which he personifies. The voice seems to take the form of birdsong. At the end of the poem, he determines that he must tread on towards this country, seeking the song of the thrushes and the solace of the land, because it is the place where he ultimately belongs.

Away from his homeland in the west, the speaker yearns to go back home. With the blowing of the warm west wind, the cherished memories of his native place in the month of April are instantly evoked. They turn him nostalgic and upset. 

I never hear the west wind but tears are in my eyes. 
For it comes from the west lands, the old brown hills. 

The west wind is the harbinger of spring. After the harsh winter, the warm west wind is soothing. It's perception reminds the speaker of the pastoral beauty of his native place, where he longs to return.

During this time, the birds begin to chirp, daffodils and “apple orchards blossom,” "the air’s like wine," “there is cool green grass there, where men may lie at rest”, thrushes can be heard “fluting from the nest,” “the young corn is green,” the rabbits run,” the sky is blue and the clouds are white, both the sun and the rain are warm and the buzzing of bees is like “song to a man’s soul” and “fire to a man’s brain.”

These pleasant memories of his native land make him all the more homesick and wistful. 

The phrases "tired feet," "bruised hearts" and "aching eyes" suggest the pain and discomfort that afflict the speaker away from his motherland. It seems to him as if the west wind is insisting on his returning home.

"Will ye not come home brother? ye have been long away,”

The urge to go back home is so strong in the speaker that he can't prolong his stay in the alien land any more. He makes up his mind to set off for the place he actually belongs to:

It's the white road westwards is the road I must tread 
To the green grass, the cool grass, and rest for heart and head, 
To the violets, and the warm hearts, and the thrushes' song, 
In the fine land, the west land, the land where I belong.

Although it's fairly odd to ask for a "summary" of a poem, I am happy to provide one here as this poem is pretty easy to understand in and of itself.

The speaker beings with definite positive images, by describing the West Wind as "warm" and full of birds chirping, "April" and "daffodills."  Next, the speaker talks about the "west land" where the west wind comes from.  It is a land full of apple orchards, lots of birds singing, "cool" green grass.  As such, it is a perfect place for people to rest. 

The third, fourth, and fifth stanzas switch to a request within quotation marks for the "brother" to come home and feel this beautiful spring.  The new speaker describes the evidence that the west wind has changed the landscape with "blue sky" and "white clouds" and "young corn" and "rain and sun."  It is definitely spring now, due to the sound of the lark and other birds, and the speaker longs for his brother to come home. 

We learn in the fifth stanza that the West Wind is the one speaking to everyone as "brother" in the last few stanzas.  The original speaker is back, insisting that he will take "the white road westwards" in order to experience all of these things.  Further, it's not just a beautiful land of spring, but it's the land where the speaker belongs.

The theme of the poem is nostalgic, describing the speaker's longing for his former home. When the west wind comes in April, it brings with it memories of his life in the unspecified "west lands."

The wind triggers him to remember the daffodils, the hills, the apple orchards, the "cool green grass," and the songbirds, such as thrushes. The wind seems to speak to him, trying to lure him home. The wind is personified and talks to him as a "brother," asking him if he doesn't want to return to a place of peace and rest and beauty. The rabbits, blue sky, clouds, and warm rains should all beckon to him and draw him home, the west wind says.

The west offers a healing balm, and at the poem's end the speaker decides he must head there:

To the violets, and the warm hearts, and the thrushes' song,
In the fine land, the west land, the land where I belong.

Thematically, the poem works on several levels. The "west land" could be the speaker's childhood or home as a young adult, or it could be a realm of the imagination, a "happy place" for him to return to in his mind when he is feeling sad or "bruised." It could perhaps also symbolize the paradise of the afterlife: in ancient British thought, the imagined western island of Avalon was an idyllic place where dead souls could rest. Because the pastoral images are nonspecific—grass, blue skies, blossoms, warm rains—it could be almost anywhere in the world, making it an almost universal place of peace that beckons to all of us. In any case, the poem's message is an eloquent expression of the human desire to return home to a place of nature and beauty.

In “The West Wind” by John Masefield the message is you can go home again to the land where you belong. The poem begins with the speaker describing the lands where the west wind blows. It is an idyllic setting of spring with the warm winds and daffodils. The west lands seem perfect to the speaker, so perfect that the thought of them brings tears to his eyes. John Masefield uses vivid imagery as he describes the land as a respite; “It’s a fine land, the west land, for hearts as tired as mine, Apple orchards blossom there, and the air's like wine.”

In the third and fourth stanza, the west wind takes over as the speaker. It tries to persuade the speaker to come home calling the speaker his “brother” while reminding him of the blue skies, the warm rain, the insects humming, and informing him that it is spring again. In the fourth stanza, the persuasion continues as the wind addresses the speaker's need for a place that takes care of weary hearts and minds.

Finally, in the last stanza, the original speaker says,

It's the white road westwards is the road I must tread

To the green grass, the cool grass, and rest for heart and head,

To the violets, and the warm hearts, and the thrushes' song,

In the fine land, the west land, the land where I belong.

He decides that he should go back to the west lands; he should go home where he belongs.

A native of the west, the speaker is well familiar with the climate and environment in his homeland when the west wind begins to blow. Regarded as the gentlest and most pleasant of all winds, it marks the departure of the cold winter and the arrival of warm spring.

The speaker is away from home probably in order to make money. When the west wind reaches his present place, he turns nostalgic. The fond memories of his homeland are aroused at once. He begins to linger in those sweet thoughts.

He recalls the beauty of his native place in the month of April. Birds begin to twitter and there are daffodils blooming here and there. The "apple orchards" too have blossomed and the air is sweet with the fragrance of “wine.” The ground is covered with "cool green grass," a perfect place to rest. Thrushes fill the atmosphere with their melodies.

It appears to him as if the soothing west wind urges him to go back to his homeland.

"It's April, and blossom time, and white is the may; 
And bright is the sun brother, and warm is the rain,-- 
Will ye not come home, brother, home to us again?"

The images of the idyllic charm of his native land in April begin to haunt his memories further. While the corn is green, rabbits run around. He pines to bask in the warmth of the sun and feel the warm rain water. He longs to hear the songs of "larks" and the buzzing of "bees."

In this season, the whole nature seems to be in a joyous state at his homeland. But the expressions “tired feet,”“bruised hearts,” and “aching eyes” evoke a sense of somberness. The west wind urges the speaker to return saying,

“So will ye not come home, brother, and rest your tired feet? 
I've a balm for bruised hearts, brother, sleep for aching eyes."

Finally, the homesick speaker can't resist himself any more to stay away from his native place and people and makes up his mind to return home. 

It's the white road westwards is the road I must tread 
To the green grass, the cool grass, and rest for heart and head, 
To the violets, and the warm hearts, and the thrushes' song, 
In the fine land, the west land, the land where I belong.

The first stanza sets the nostalgic tone of the poem by expressing the speaker's longing for the "west lands." I will copy the first stanza of the poem below. Then I will discuss it in greater detail:

It's a warm wind, the west wind, full of birds' cries;
I never hear the west wind but tears are in my eyes.
For it comes from the west lands, the old brown hills.
And April's in the west wind, and daffodils.

The poem opens with the warm west wind bringing up memories that evoke a bittersweet mixture of joy and sorrow in the speaker. The west wind stirs his memories of spring: it is warm, it makes him think of bird cries (I live in the country now and know that birds definitely make far more racket in the spring than the winter), and brings with it a vision of daffodils—flowers associated with spring.

These memories are sweet because they recall a happy time in the poet's life. However, they are bitter or sad because he longs to be back in his beloved west lands. He repeats the word "west" so many times that it becomes a word of longing and lament.

These "west lands" may be the lands of his early childhood in Herefordshire, which is near Wales and therefore on the west side of England. April would be a month of warm breezes and daffodils all over the British isles.

Whatever the case, the poet is deliberately vague about the west lands but longs to be back in a natural setting that inspires fond memories.