The three principal regions of La Rioja are Rioja Alavesa, Rioja Alta and Rioja Baja with each area producing its own unique expression of Rioja wine. Most of the territory subjected to the Rioja Protected designation of origin is in the La Rioja region, even though their limits do not coincide exactly. There is a narrow strip in the left bank of the Ebro river lying in the southernmost part of Álava included in the La Rioja wine region, whereas the south-southwestern part of the La Rioja region is not a part of this Protected designation of origin.
Rioja Alta and Ebro
Located on the western edge of the region and at higher elevations than the other areas, the Rioja Alta is known more for its "old world" style of wine. A higher elevation equates to a shorter growing season, which in turn produces brighter fruit flavors and a wine that is lighter one the palate.
Despite sharing a similar climate as the Alta region, the Rioja Alavesa produces wines with a fuller body and higher acidity. Vineyards in the area have a low vine density with large spacing between rows. This is due to the relatively poor conditions of the soil with the vines needing more distance from each other and less competition for the nutrients in the surrounding soil.
Unlike the more continental climate of the Alta and Alavesa, the Rioja Baja is strongly influenced by a Mediterranean climate which makes this area the warmest and driest of the Rioja. In the summer months, drought can be a significant viticultural hazard, though since the late 1990s irrigation has been permitted. Temperatures in the summer typically reach 35 °C (95 °F). A number of the vineyards are actually located in nearby Navarra but the wine produced from those grapes belongs to the Rioja appellation. Unlike the typically pale Rioja wine, Baja wines are very deeply coloured and can be highly alcoholic with some wines at 18% alcohol by volume. They typically do not have much acidity or aroma and are generally used as blending components with wines from other parts of the Rioja