roaring forties

The belt of strong westerly winds found between 40 and 50 degrees south latitude, where there is almost no landmass to slow the air circling the globe. Sailors have named the progressively more violent zones beyond: the Furious Fifties and the Screaming Sixties.

Etymology

English nautical, in use since the early 19th century. The "forties" are the degrees of latitude; the "roaring" is self-evident to anyone who has sailed through them.