'Hass' avocado is the most important avocado variety cultivated worldwide. In Chile alone, there are nearly 40,000. ha, distributed between the IV and VI regions, with production areas located close to both the coast and to the hills. Given the increasing competitiveness of fruit export markets, the quality of organoleptic attributes is a key issue in consumer acceptance. The quality of avocados is related to many attributes, especially oil content and firmness (among others), and these attributes are influenced by storage, growing and environmental conditions, as well as the stage of maturity/ripening.This study measured the fatty acid profiles of avocado fruits during two seasons from 12 localities cultivated with the variety 'Hass.' Fifty additional variables were measured, including climate, nutrition, vegetative development, and agricultural management (called pre-harvest variables). The data obtained were analyzed with a partial mean squares multivariate regression (PLS). The analysis showed that the contents of oleic, palmitic, and palmitoleic acids were influenced by climatic and nutritional factors, with mean annual maximum temperature proving most important. In localities with lower temperatures, the 18-carbon fatty acid content increased, and the 16-carbon fatty acid content decreased. Moreover, the N and Mg contents in the mesocarp at harvest were related to the contents of palmitic and palmitoleic acids, and when the levels of N and Mg increased in the mesocarp, the 16-carbon fatty acid content decreased.