A pattern of intraseasonal to interannual variability in precipitation and surface winds for the eastern equatorial Indian Ocean (EEIO) during 1979 to 1999 is described using combined Empirical Orthogonal Function (EOF) analyses. The main features of the positive phase of the EEIO mode are 1) enhanced precipitation to the south of the island of Sumatra, 2) suppressed precipitation in the central equatorial Indian Ocean, 3) surface westerly wind anomalies directed from the dry toward the wet region, and 4) southeasterly wind anomalies which meet the westerly anomalies in the vicinity of the enhanced precipitation. A relationship was found between the precipitation gradient of the EEIO mode and the five strongest El Ni¿o events since 1979 (1982/83, 1986/87, 1991/92, 1994/95, and 1997/98). For the cases when the interannual component of the gradient reached a positive peak followed by significant power (94%) in the 30--60 day component of the gradient roughly a season later, an El Ni¿o was observed to develop.