A west wind is a wind

Wind

Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...

 that blows from the west, in an eastward direction. In Western tradition, it has usually been considered the mildest and most favorable of the directional winds.

In Greek mythology

Greek mythology

Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...

, Zephyrus was the personification of the west wind and the bringer of light spring and early summer breezes; his Roman equivalent was Favonius. In the myth of Cupid and Psyche, Zephyrus was the attendant of Cupid, who brought Psyche to his master's palace.

Geoffrey Chaucer

Geoffrey Chaucer

Geoffrey Chaucer , known as the Father of English literature, is widely considered the greatest English poet of the Middle Ages and was the first poet to have been buried in Poet's Corner of Westminster Abbey...

wrote of the "swete breth" of Zephryus, and a soft, gentle breeze may be referred to as a zephyr, as in Shakespeare's Cymbeline (IV, ii): "They are as gentle / As zephyrs blowing below the violet, / Not wagging his sweet head."