Mistral is an atmospheric phenomenon that occurs mostly in the winter and spring in the Gulf of Lion creating a cold, strong northwesterly wind along the coast, particularly from Marseille to Toulon, France. It is an example of a katabatic wind, which is caused by air that is cooled over the mountains by the presence of a high pressure system or radiative cooling. In the case of the Mistral, air is cooled above the Massif Central, the central plateau of France, and the Pyrenees and then flows down into the Garone valley because its density is higher than the one of the surrounding air. The presence of Garone and Rhone valley creates a funnel effect, speeding up the current towards the Gulf.
In Marseilles, on about half of the days in the year the weather is characterized by the cold winds of the Mistral. These winds may affect the weather in North Africa, Sicily and Malta or throughout the Mediterranean, particularly when low pressure systems form in the Gulf of Genoa.
