 The volcano lies south of the so-called "Arid Diagonal", and most precipitation falls during winter.This aridity is caused by the rain shadow effect of the Subandean Ranges, which block moisture from the Atlantic Ocean.One andesitic lava flow on the northwestern slope of Incahuasi has yielded two ages, one of 1.15 ± 0.5 million years ago and another of 710,000 ± 80,000 years ago.