Monsoon winds are seasonal reversing winds that cause corresponding changes in precipitation. They are caused by a seasonal shift in the direction of the wind, which happens when the temperature of the land and the temperature of the water are different as seasons change. Monsoons always blow from cold to warm, and in the summer, warm air rising off the land creates conditions that reverse the direction of the wind. The major monsoon systems of the world consist of the West African, Asia–Australian, the North American, and South American monsoons.

Some key points about monsoon winds are:

• Definition: A monsoon is a seasonal change in the direction of the prevailing, or strongest, winds of a region.
• Cause: Monsoons are caused by different warming trends over land and sea, though other factors may be involved. Seasonal changes in temperature are large over land but small over ocean waters, and monsoons blow from atmospheric heat sinks toward heat sources.
• Effects: Monsoons cause wet and dry seasons, and they can bring heavy rainfall to an area. When the wind changes direction in the winter, it is called a winter monsoon, which is usually dry.

While many of the most well-known monsoons are in Asia, monsoons can happen anywhere there is a seasonal difference in temperature between the land and water, usually in tropical and subtropical climates.