The mistral is a strong, cold, northwesterly wind that blows from southern France into the Gulf of Lion in the northern Mediterranean, with sustained winds often exceeding 66 km/h (41 mph), sometimes reaching 456 km/h (283 mph). It is most common in the winter and spring, and strongest in the transition between the two seasons. Periods of the wind exceeding 30 km/h (19 mph) for more than sixty-five hours have been reported.

The mistral takes place each time 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 lower elevations between the foothills of the Alps and the Cevennes. The conditions for a mistral are even more favorable when a cold rainy front has crossed France from the northwest to the southeast as far as the Mediterranean.

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