The Climate…and its Influences
When you look at a map of Switzerland it doesn’t seem to offer a lot in terms of growing vines. About 70% of the country is mountainous – 60% from the Alps and 10% from the Jura range. The mountains not only provide physical challenges and barriers, but they also greatly influence the climate.
Swiss climate is best described as continental – meaning cold winters, short and hot summers, and long warm autumns. Rainfall also varies considerably, with some years being very wet, and other years rather dry. Weather is carried into Switzerland by differing winds, jet streams, and weather fronts. The map below shows how the different air masses influence the climate and weather of Switzerland. During the winter, most of the weather is influenced by the polar and arctic air mass, which brings snow when coming from the North Sea and very cold icy winds when coming from the eastern continent over Russia and Poland. During the spring and summer, Switzerland’s weather is mostly influenced by the Atlantic air mass, which bring warm and wet winds. Sometimes during the summer months, hot winds from the Sahara flow northward, bringing hot and dry weather.
As the weather arrives into Switzerland, it collides with the mountains and creates strange wind patterns. These winds can create some unusual micro-climates within Switzerland – everything from surprisingly arid environments to cold and wet regions. The map below shows how some of the winds are normally deflected as they arrive in Switzerland.
The shifting wind patterns create dramatic differences in weather. Hallau, in the canton of Schaffhausen, receives an average annual rainfall of 830mm (Florence in Italy also receives an average of 830mm of rain, and the Napa Valley in California receives an average of 894mm). In comparison, Wädenswil, on Lake Zürich, gets 1,300mm of annual rainfall, St. Gallen 1,500mm, and Tessin (in the sunny part of Switzerland) 1,700mm. In terms of overall sunshine, Tessin and Wallis receive around 2,000 hours of annual sunshine, Geneva has about 1750 hours of sunshine each year, and the wine region of Graubünden has 1,800 sunny hours. The most surprising climate of Switzerland is found in canton Wallis. This area receives an average annual rainfall of only 574mm, which is comparable to Apulia in southern Italy (550mm). With limited rainfall and sunshine comparable to the French Bordeaux, it is no wonder that irrigation is necessary in this area just to grow grapes.
The warm winds in Switzerland, called the Föhn (meaning hairdryer), help vineyards in several ways. In Wallis, the warm winds create favorable conditions for grapes to grow in very high altitudes – sometimes as high as 1,100 meters. In the Bündner Herrschaft region of Graubünden, the winds can create temperatures of up to 25° C in late fall. These higher temperatures make it possible for grapes to ripen properly in this region.
The Föhn not only provides warm temperatures, but also helps keep the vineyard dry and airy. Vines that stay wet are often quite susceptible to many diseases, so the winds provide a sort of protection. Sometimes, however, the winds are too strong and they will break grape branches.
Lakes and rivers also affect regional climates. Water reflects sunlight and creates more equable temperatures with less extremes between hot and cold. The presence of water will also increase humidity, and at certain times during the year, create fog. Fog can be an advantage sometimes in growing grapes, as it will create a favorable environment for ‘noble rot’ to occur. Noble rot is responsible for creating some of the world’s finest sweet wines.
The presence of mountains not only deflects the weather, but in some circumstances mountains can completely block weather. This is true in the areas around Schaffhausen and Thurgau. The substantial black forest area of southern Germany creates a natural barrier and protects certain northern areas of Switzerland from strong winds and rain.
The unusual regional weather patterns in Switzerland create certain areas of this mountain country which are actually quite attractive to growing grapes. That is, of course, until one is faced with the physical challenges of growing grapes on a mountain slope.