The southwest monsoon is a summer-time rainy pattern that moves over India from south to north.  It usually starts in June and lasts through September.  Since India has lots of rain-fed crop production, the timing and quantity of monsoon rains is really important to planting and yield of Indian crops, including cotton.  In years when India has a weak or late monsoon, it can reduce cotton supplies and affect world cotton prices.   In years when India has a timely, above average monsoon, the resulting surplus of Indian cotton can result in exported surpluses that compete with U.S. exports.