gregale, strong and cold wind that blows from the northeast in the western and central Mediterranean region, mainly in winter. Most pronounced on the island of Malta, the gregale sometimes approaches hurricane force and endangers shipping there; in 1555 it is reported to have caused waves that drowned 600 persons in the city of Valletta. A gregale that lasts four or five days is usually the result of a flow of air from central or southern Europe toward Libya. One that lasts only one or two days is caused by the passage of a low-pressure centre over the southern Mediterranean.