Indonesian Weather The extreme variations in rainfall are linked with the monsoons. Generally speaking, there is a dry season (June to September), influenced by the Australian continental air masses, and a rainy season (December to March) that is the result of mainland Asia and Pacific Ocean air masses. Local wind patterns, however, can greatly modify these general wind patterns, especially in the islands of central Maluku–Seram, Ambon, and Buru. This oscillating seasonal pattern of wind and rain is related to Indonesia’s geographical location as an archipelago between two large continents. In July and August, high pressure over the Australian desert moves winds from that continent toward the northwest. As the winds reach the equator, the earth’s rotation causes them to veer off their original course in a northeasterly direction toward the Southeast Asian mainland. During January and February, a corresponding high pressure system over the Asian mainland causes the pattern to reverse. The resultant monsoon is augmented by humid breezes from the Indian Ocean, producing significant amounts of rain throughout many parts of the archipelago.