The main feature of this valley is the maritime influence of the Pacific Ocean, which produces a morning mist and breezes that acts as a temperature moderator. This favours the best development of the vineyard, and demands special care if the desired ripening is to be achieved. The varieties that grow best in this zone are Chardonnay, Sauvignon Blanc and Pinot Noir.
This valley is the one with the greatest tradition in wine-production in Chile. It has a temperate climate and the soils are alluvial in origin, very stony, with good drainage. Its climatic conditions favour the development of red wines, mainly Cabernet Sauvignon.
In general, the climate in this region can be described as sub-humid Mediterranean, though the valley is renowned for having the greatest climatic diversity between its different areas. Old vineyards with País or Carignan grapes are to be found.