The monsooning process consists of exposing natural coffee beans, in 4- to 6-inch-thick piles, to moisture-laden monsoon winds in a well-ventilated brick or concrete-floored warehouse. This process is carried out on the West Coast of India, making use of the winds from the Arabian Sea during the southwest Monsoon months of June through September.
The processing begins with top-grade beans, Arabica cherry AB, that has already been processed by the dry method. To equalize moisture absorption, the beans are raked frequently, followed by bulking and re-bagging at regular intervals. During this 12- to 16-week process, the beans absorb moisture in stages, swelling to nearly twice their original size and developing colors ranging from pale gold to light brown. After several weeks, the coffee is re-bulked, graded again, bagged and moved to a drier region for longer-term storage.