During the period 1968--1999, the character of circum-Antarctic anomalies in sea level pressure, sea ice edge, and sea surface temperature changed substantially. An Antarctic Circumpolar Wave (ACW) is only clearly visible in the period 1985--1994. Before, and perhaps after this, the signal, particularly in sea level pressure, is quite different with no clear sign of precession. Accompanying the change from precessional to nonprecessional modes is a change in the spatial pattern of variability and a change in the predictability of atmospheric anomalies from oceanic forcing. Evidence from general circulation model integration suggests that during the precessional mode of the ACW, there is enhanced predictability, as would be required to support a coupled ocean--atmosphere interaction.