Mistral – what a cool name. ”A strong, cold north-westerly wind that blows through the Rhône valley and southern France towards the Mediterranean” – according to the Oxford Dictionary. Which is precisely where Provence is situated. The air is dry, the sky bright and clear and the temperature usually gets a lot cooler. Wind speeds can exceed 90 kilometres an hour with an average of fifty kilometres an hour during the day. During the night the winds calm down but it is not uncommon for the winds to blow consistently for two to three days.
The strong wind from the north has a largely positive influence on the local viticulture. It cools the grapes from the heat and – particularly helpful – dries the grapes after rain, providing some protection against grape rot and grape diseases. But it can also damage vines that are not securely trained and protected by hillside landforms. In areas where the wind is particularly strong, the ideal vineyard locations are on hillsides facing south towards the sea, with the hill providing some shelter from the mistral’s strength. The local Provençal farmhouses (Mas) are built facing south for the same reason.
Where did it get its name from?
In the south of France, the name comes from the Languedoc dialect of the Occitan and means “masterly”. The same wind is also known as mistrau in the Provençal variant of the Occitan language. Or maestrale in Italian and Corsican.
What causes the Mistral?
The mistral happens when there is an anticyclone, or area of high pressure, in the Bay of Biscay and an area of low pressure around the Gulf of Genoa. When this happens, the flow of air between the high and low pressure areas draws in a current of cold air from the north which accelerates through the foothills of the Alps. The conditions are even more favorable when a cold rainy front has crossed France from the northwest to the southeast as far as the Mediterranean.
This cold, dry wind usually causes a period of cloudless skies and luminous sunshine, which gives the mistral its reputation for making the sky especially clear. There is also, however, the mistral noir, which brings clouds and rain. The mistral noir occurs when the Azores High is extended and draws in unusually moist air from the northwest.
The mistral helps explain the sunny climate and clarity of the air of Provence.
When other parts of France have clouds and storms, Provence is rarely affected for long, since the mistral quickly clears the sky. In less than two hours, the sky can change from cloudy and grey to completely clear. The mistral also blows away the dust, and makes the air particularly clear, so that during the mistral it is possible to see mountains 150 kilometres away. This clarity of the air and light attracted many artists to the South of France, just look at Cezanne if you are visiting Aix en Provence… The mistral has the reputation of bringing good health, since the dry air dries stagnant water and the mud, giving the mistral the local name ‘mange-fange’ (mud-eater in english). It also blows away pollution from the skies over the large cities and industrial areas. The vegetation in Provence, which is already dry because of the small amount of rainfall, is made even drier by the wind, perfect for grape vines!
So if you happen to visit during the Mistral season, hold on to your hats!
Below is an impression of the Mistral and the vineyards (video quality possibly influenced by the strong wind?)