A monsoon (from the Arabic mausim, which means ‘season’) arises due to a difference in temperatures between a landmass and the adjacent ocean. The seasonal reversal in wind direction during a year is called the monsoon.
The wet monsoon begins when winds bringing cooler, more humid air from above the oceans to the land. A dry monsoon typically occurs between October and April. The apparent position of the Sun with reference to the Earth oscillates from the Tropic of Cancer to the Tropic of Capricorn. Instead of coming from the oceans, the winds tend to come from drier, warmer climates such as from Mongolia and northwestern China down into India.