During summer 1998, record reductions in ice cover occurred in the Beaufort and Chukchi seas. Open water formed earlier than in prior years, and September ice extent in this region was 25 percent less than the previous minimum for 1953--1997. Seven percent of the Arctic Basin that had been perennially ice covered was ice-free in 1998. This reduction in western Arctic ice extent can be attributed in part to preconditioning by light-ice cover in autumn 1997 and to atmospheric circulation patterns during the following winter through autumn that favored southerly and easterly winds. Such decreases in northerly winds, and the associated weakening or displacement of the Beaufort Gyre, is found to be typical of winters that precede years with below-normal ice extent in the western Arctic. ¿ 1999 American Geophysical Union