Sea surface temperature (SST) variations in the equatorial eastern Pacific (0–10°S, 180–90°W) are compared with variations in atmospheric temperature, circulation, rainfall and trace-constituent amount. Significant at the 99.9% level (taking into account the serial correlation in the seasonal data) is the zero-lag correlation of −0.62 between this SST and the Southern Oscillation Index (normalized pressure difference between Tahiti and Darwin) during 1932–79, the correlation of 0.72 between this SST and the zonally averaged temperature in the tropical troposphere two seasons later during 1958–79, and the correlation of −0.62 between this SST and Indian summer monsoon rainfall 1–2 seasons earlier during 1868–1977. Significant at the 99% level is the correlation of 0.67 between this SST and rate of increase of CO2 at the South Pole 2–3 seasons later during 1965–76, and significant at the 95% level the correlation or 0.37 between this SST and rate of increase of CO2 at Mauna Loa one season later dur... Abstract Sea surface temperature (SST) variations in the equatorial eastern Pacific (0–10°S, 180–90°W) are compared with variations in atmospheric temperature, circulation, rainfall and trace-constituent amount. Significant at the 99.9% level (taking into account the serial correlation in the seasonal data) is the zero-lag correlation of −0.62 between this SST and the Southern Oscillation Index (normalized pressure difference between Tahiti and Darwin) during 1932–79, the correlation of 0.72 between this SST and the zonally averaged temperature in the tropical troposphere two seasons later during 1958–79, and the correlation of −0.62 between this SST and Indian summer monsoon rainfall 1–2 seasons earlier during 1868–1977. Significant at the 99% level is the correlation of 0.67 between this SST and rate of increase of CO2 at the South Pole 2–3 seasons later during 1965–76, and significant at the 95% level the correlation or 0.37 between this SST and rate of increase of CO2 at Mauna Loa one season later dur...