Prevailing westerlies are winds that blow from the west that occur primarily between 30 and 60 degrees latitude. Prevailing westerly winds form above subtropical highs in the Northern Hemisphere and below the subtropical highs of the Southern Hemisphere. These winds form in the west, and primarily blow from west to east, although they occasionally blow northward or southward.
Westerly winds are one of several types of winds that form at various latitudes and geographical regions around the world. Closer to the equator, prevailing winds are referred to as doldrums and are generally much less forceful than westerly winds. These winds may come from any one of the primary cardinal directions, although at times they are virtually nonexistent. Trade winds are winds that occur on latitudes up to 30 degrees north and south of the equator and blow predominantly from the east.
Air pressure and temperature are primarily responsible for generation of the various winds, and both play a big part in influencing the direction from which wind blows. At the equator, heat generated from the sun causes air to rise and form an area of low pressure that gives rise to moving air that may generate from various directions. Westerlies vary in strength and may change with seasonal weather patterns or with sudden changes atmospheric changes, such as storms and the presence or absence of fronts and other weather systems.