Cerro Tronador is in the Wet Andes, a zone of high precipitation of both snow and rain. The humid temperate climate of the southern Andes has allowed several glaciers to develop due to high accumulation rates. Most of the precipitation is produced by western frontal systems from the Pacific. Located in the middle of the Andean massif at a latitude of 41° S, Tronador is part of an alpine landscape of fjords, glacial lakes, and U-shaped valleys. The forming of the landscape took place during the Quaternary glaciations, periods during which the whole area was covered by the Patagonian Ice Sheet. The volcano grew during the glacials and interglacials of the Pleistocene but became practically extinct in the late Middle Pleistocene, approximately 300 ka ago, due to a shift in the active front of the Southern Volcanic Zone to which it belongs. Since then, glaciations and other erosive processes shaped the mountain freely without new output of lava or tephra. As in the case of nearby Lanín volcano, Tronador is composed mostly of basalts, and has seen a decline in activity as the Osorno and Calbuco volcanoes grow further west.