AbstractIt is now clear that conditions in the tropical Pacific Ocean and the overlying atmosphere can have significant associations with the seasonal—mean circulation of the mid‐latitude atmosphere, particularly in winter. Notable is a tendency for an intensification of the climatological standing wave pattern over the North Pacific and North America during the warm tropical conditions associated with El Niño/Southern Oscillation (ENSO) events. However, the actual mid‐latitutde circulation anomalies do show a great deal of variability among individual ENSO years. This paper addresses the question of whether the variability of the mid‐latitude response to ENSO events can be attributed to differences in the details of the tropical anomalies from event to event. The investigation embraced the period 1899–1982 and employed data on tropical sea surface temperatures (SSTs), tropical rainfall, and mid‐latitude atmospheric surface pressures and air temperatures.The results suggest that a major factor in determining the strength of the Northern Hemisphere extratropical response is the SST anomaly in the far western Pacific/Indonesian region. In particular, it appears that the strong extratropical teleconnections with ENSO events occur more frequently when the SST in the far western Pacific is anomalously warm (or at least not overly cold). This finding appears to be consistent with the results of at least some recent numerical experiments conducted with comprehensive general circul