There are a number of factors which contribute to an individual vineyard’s terroir but climate goes a long way towards understanding a particular wine region. In the case of Spain and Portugal, climate is governed by the competing influences of a number of different Climate Components.
This provides a handy conceptual framework, but to understand the climate we need to look at real data compilations. A GIS climate database was launched in 2000 by the University of Barcelona, which integrates data from over 2,000 weather stations. Aimed at providing a better understanding of the link between climate and vegetation, this database integrates climate data for the period 1951-1999 at a spatial resolution of 200 m.
Summary information from this database was subsequently used to produce the Atlas Climático Digital de la Península Ibérica (PDF)¹, which is a very useful document for anyone interested in understanding Spain or Portugal’s wine regions and from which the following maps are taken.
The topographic map of the Iberian Peninsula shows elevation at 300 m intervals, which brings out major structural elements. Note, for example, how Castilla y Leon (including the Ribera del Duero wine region) is a high plateau surrounded by mountains on three sides. By contrast, the Ebro Valley (including the Rioja wine region) has a much lower elevation and a link with the Mediterranean. Jerez meanwhile is located on low-lying coastal plain at the mouth of the Guadalquivir River basin.
Latitude, continentality and elevation all influence average temperature. Note the cool average temperatures of Castilla y Leon, the warmer temperatures of the Ebro Valley and the hot temperatures of Guadalquivir River Basin. The Atlas Climático also includes average minimum and average maximum temperature maps, which paint a much fuller picture of temperature patterns across the peninsula. From even a cursory examination of these maps, Ribeira del Duero and Rioja would be expected to be quite different wine regions – notwithstanding the fact that they both grow mainly Tempranillo.
The average precipitation map brings out the strong influences exerted by the Atlantic and by elevation. Note the extreme range of precipitation across the peninsula. For parts of northeastern Portugal, much of coastal Galicia and along the southern borders of the Pyrenees, annual precipitation is >1,500 mm. By contrast, in southeast Spain the annual precipitation is <300 mm. From a wine-growing perspective, Galicia’s wine regions understandably exist without any need of irrigation. Throughout many other parts of Spain and Portugal, either irrigation is required or yields per vine are rather low.
In addition to the Atlas Climatico, very useful climate data can be found in the Iberian Climate Atlas (PDF)², which summarises climate data for the period from 1971-2000. This atlas includes many additional maps such as average temperatures by month, average number of days with minimum temeratues <0°C and average number of days with maximum temperatures >25°C.
It should be remembered that maps from both these atlases show average values. Year on year variation, which greatly influence the size and quality of the harvest, require a different type of investigation.
¹ Ninyerola M, Pons X y Roure JM. (2005) Atlas Climático Digital de la Península Ibérica. Metodología y aplicaciones en bioclimatología y geobotánica. ISBN 932860-8-7. Universidad Autónoma de Barcelona, Bellaterra, 45pp
² Iberian Climate Atlas (2011) Produced by the State Meteorological Agency of Spain and by the Institute of Meteorology, Portugal. ISBN: 978-84-7837-079-5, 80pp