 In 1956, a mistral wind from the northwest reached the speed of 180 kilometres an hour at Nice airport.Sometimes in summer the sirocco brings high temperatures and reddish desert sand from Africa (see Winds of Provence).Rainfall is infrequent, 63 days a year, but can be torrential, particularly in September, when storms and rain are caused by the difference between the colder air inland and the warm Mediterranean water temperature (20–24 degrees C.).