The total area of Spanish vineyards is in the region of 1.2 milion hectares. That is enormous and about 300,000 hectates larger than either the France or Italian wine-growing areas.
Yet less wine is produced than in either of the other two countries, at approximately 35,5 milion hectolitres, a vast 20 milion hectolitres less than France or Italy.
The difference in production volumes in partly accounted for by the large proportion of Denominación de Origen wine. Spain produces relatively smaller volumes of vino de la tierra (country wine or vin de pays) than France or Italy.
The majority of Spanich wines originates from Catalonia, Valencia, and La Mancha. Regions such as La Rioja, Aragon, Levante, and Andalucia produce quality wine in much lower volume.
California’s climate is quite varied, which is not surprising given the large area of the state. In rough terms the climate on the coast is similar to the Mediterranean with warm summers and mild winters. Summer in the Central Valley is exceptionally hot and dry, while summer in the area immediately behind the coast is much moister and can be misty.
The highest temperatures are in the Central Valley and the mildest are on the coast. The North Coast vineyards get the most rainfall. The soil is also varied as a result of the many earthquakes that hane occured throughout the area. The soil varies from alluvial and sedimentary deposits to strata of volcanic origin.
The notion of terroir that is so strong in Europe is not given much credence in California. The variety of grape is far more likely to be chosen as suitable for the climate than the soil.