Valle Central or Central Valley is the area where, traditionally, most of Chile’s wine grapes have been grown. The area is a 600 mile-long plateau which reaches as far south as Puerto Montt and is separated from the Pacific Ocean to the west by a relatively low coastal range (1,000 to 2,600 feet). The coastal range is high enough to precipitate rainfall in their immediate shadow and are separated from the Argentine Mendoza wine region to the east by the Andes, which can reach altitudes of 23,000 feet. Vines will grow up to 1,800 feet on the western slopes of the Central Valley and 3,000 feet on the sunnier eastern slopes of the Andes.
The Central Valley is dissected by rivers which, during the growing season, carry torrents of melted snow from the Andes to the Pacific — irrigation made easy. Though there are distinct variations in climate, even between sub-regions, the Central Valley is generally Mediterranean with warm, dry summers and rainfall averaging 14 – 31 inches a year, restricted to the winter, thanks to the effect of the Pacific high-pressure area. Rainfall in the Central Valley tends to increase both in the south and west – in the shadow of the coastal range. On the western edge of the valley, summer temperatures average 59 to 64 degrees F and may rise to 86 degrees F with clear skies, strong sunlight and low humidity of just 55 to 60 percent. On the eastern edge of the valley, however, under the influence of cold air drainage from the Andes at night, there is higher humidity and much greater temperature variation resulting in particularly good levels of acidity and color in the grapes.