There are a myriad of reasons why a wine tastes the way it does. The type of grape certainly is the primary factor, as well as winemaking. However, the reason for certain grape varieties performing well in one region, yet horribly in others, boils down to each region’s overall climate.
Grape varieties are chosen by a vineyard based on their physiological characteristics, and how well they can adapt to the climate. Thick skinned grapes, for example, perform best in warm climates, while thin skinned grapes perform best in cooler climates. A grape’s bunch characteristics also play a significant role. A tight bunch would be susceptible to lots of rain as the grapes would rot with all the excess moisture. Inversely, varieties with a loose bunch would easily dry out in very hot climates.
Viticulturalists use the Winkler Index which defines regions by accumulative “growing degree-days”, or a total number of daylight hours within a growing season above 50 degrees Fahrenheit. This scale has five regions, with one being the coldest and five being the warmest. Quality table wine is only produced within the first three regions, with the last two reserved for table grapes.
This scale can be summarized by three overall regional types which are suitable for wine grape production. Each climate has their own characteristics that benefit certain varieties: Continental, Maritime, and Mediterranean.
Continental Climate
Definition: a wine region located within the interior of a large land mass void of moderating effects of water.
Examples: Mendoza, Columbia Valley, Rioja/Ribera del Duero, Piedmont, interior Loire Valley, Austria, Northern Rhone, Burgundy, Douro
Continental climates can easily be defined as interior areas within a landmass that have four distinct seasons. This has two important effects on grape growing. Firstly, due to cold winters, the vines can completely hibernate, however they must be hearty enough to sustain life through sub-freezing winters. The most important effect of continental climate on grapes are severe temperature swings during the growing season, also known as diurnal shift. Warm days increase sugar content in the grapes, while cold nights maintain high acidity. Grapes produced in these regions should be tolerant to drought, late budding, and early ripening.
Overall, characteristics of the final wine have moderate to high acidity, moderate to low alcohol, and fruit profile tends to be more reserved with plenty of complexity. Light exposure is very important in these regions to allow grapes to fully ripen since these regions are oftentimes cooler. Maximizing sun exposure gives the grapes a better shot at achieving full phenolic ripeness.
Maritime Climate
Definition: a wine region that is near a large body of water that moderates temperatures
Examples: Bordeaux, Sonoma Coast, Santa Barbara, Willamette Valley, Cape Point, New Zealand, Germany, Champagne, Alsace
Maritime climates tend to be the most marginal regions in the world for grape growing. Areas that would otherwise be too cold for ripening grapes are kept moderated by nearby water mass. The water mass is not exclusively oceanic, as the Mosel wine region, for example, is moderated by the Mosel River. Grapes grown in these regions tend to have thin skin and are late budding and early ripening to accommodate shorter growing seasons. Bordeaux is the obvious exception here. While cooler than one may think, the region’s proximity to the Atlantic Ocean helps to moderate heat, which allows the wines to maintain higher acidity.
The hallmark of maritime influenced wine is balance – moderate to high acid, and moderate to low alcohol. Wine from these regions tends to be very long lived.
Mediterranean Climate
Definition: a wine region that is relatively warm and long growing season, and has similar meteorological characteristics to the Mediterranean
Examples: Napa Valley, Provence, Tuscany, Southern Rhone, Barossa, Stellenbosch
Mediterranean climates have very long and sunny growing seasons without much seasonal variance. These are the warmest wine growing regions, and the grapes used in these regions are the most hearty: thick skins, drought tolerant, deep roots, and tight bunches – all elements that allow grapes to perform in hot, dry weather.
Wine produced from these regions tend to be the most fruit forward, highest in alcohol, and lowest in acidity. If you enjoy full-bodied reds, look for wine produced in these climates. Generally, wine produced in Mediterranean climates do not age as well as compared to maritime or continental climates due to lower acidity. High production can also be an issue due to the long warm growing season as it can deplete fruit quality, so vineyard managers will often aggressively “green harvest” or prune back unripened fruit to maintain concentration. Excessive production can water down the quality of fruit resulting in a poor quality wine.
