Strong seasonal winds that blow across Southeast Asia are called monsoons.
A monsoon is more precisely a seasonal reversal in prevailing winds, usually accompanied by a major change in rainfall. During a summer monsoon, heated land helps draw moist air inland from nearby seas, often producing intense rain. In the winter, the circulation can reverse as land cools faster than the ocean, bringing drier air toward the region.
Southeast Asia lies within the broader Asian monsoon system. The East Asian monsoon affects Indochina, the Philippines, southern China and neighboring areas, while related monsoon circulations extend across the Indian Ocean and South Asia. Mountains, coastlines and ocean temperatures strongly influence where the rain falls.
A common mix-up is treating “monsoon” as simply another word for a rainstorm or rainy season. Technically, the winds and their seasonal reversal are central to the term; the heavy rains are a consequence of the circulation. The word comes from the Arabic mausim, meaning “season.”