Local temperature is probably the most important climatic aspect. While many viticultural areas tend to be near moderating bodies of water, some continental climates are also suited to fine wine production. Largely because of this climactic variable, the length of the growing season varies in different regions.
UC Davis Heat Summation Scale
The UC Davis heat summation scale measures the temperature of a vineyard in degree days. It suggests growing certain varietals in five different climates, but these are only recommendations. Successful growers delve much deeper into the details of the microclimate before they decide to plant grapes and produce wine.
Red and white grapes that enjoy a lot of sun exposure tend to make fuller bodied wines.
Wine grapes need at least 1,400 hours of annual sunlight during the growing season to ripen properly. This is also increases the temp, causing grapes to mature increasing the quality of the wine.
Fog exposure is one of many factors that influence the temp of a vineyard. It will moderate extremes, cooling warm days and warming cold nights and mornings. It is also responsible for botrytis cinerea, or “noble rot.” This aspect of climate plays a very important role in the finished wine.
While some wind exposure is considered a good thing, excessive amounts can stop the metabolic process of grapevines and produce unfinished wines. Like other climactic variables, it has a moderating effect on extreme climates. Some growers have machines in their vineyards to warm vines on cold, spring mornings.
The amount of rainfall a wine region receives has a large impact on the type and quality of the grapes and wine produced. An excessively wet summer can induce harmful mildew in a vineyard. Additionally, precipitation shortly before harvest may dilute sugar levels and adversely affect the finished wine, thus the climate must be right. However, vines need no less than 22 annual inches of precipitation to survive. As usual, balance is critical.
Too much humidity in the vineyard encourages mildew and disease. But, like other climatic variables, humidity is responsible for botrytis cinerea. Wines made with grapes affected by “noble rot” are extremely sweet and have a luscious feel on the palate.
The vineyard climate has a very important role on wine grapes and the finished wine. There are many aspects of climate, and learning about how they affect wine will give you insight into why certain areas are better than other for wine grape growing.