The province of Mendoza in west-central Argentina, just east of the Andes Mountains that form Argentina's natural border with Chile, dominates the wine industry in Argentina, producing three-quarters of the country's wine. For many wine lovers around the world, Mendoza is Argentine wine. Virtually all photos you're likely to see of the vineyards of Mendoza show in the background the towering snow-capped Andes, the highest peaks of which dwarf the tallest mountains in the western U.S.
Mendoza is a semi-desert with hot daytime temperatures, cool nights, and a cold winter. Depending on the site, rainfall is generally barely 8 to 10 inches a year, falling mainly during the summer months, as the high Andes range blocks moist air coming from the western, Pacific coast of South America. The greatest weather threats in Mendoza are spring frost and sporadic, but sometimes devastating, hailstorms. Harvest rains are rarely a problem, although it should be noted that the summer and harvest of 1998 were a disaster due to conditions caused by El Niño.
The effects of heat are partly mitigated by planting at high altitude, with Mendoza's best vineyards at 3,000 to 5,000 feet. The best sites are not far east of the Andes. Farther to the east, as the land slopes gently down from the mountains, temperatures are considerably hotter, soils are more fertile, and wine quality is lower. Irrigation is necessary throughout the Mendoza region. Happily, Mendozas growers are able to rely on an ingenious and extensive system of hundreds, if not thousands, of irrigation canals that were originally dug by natives of the area in the 16th century to bring pure, frigid water from the Andes.