Tropospheric temperatures tended to cool after the Agung (8°S) eruption in 1963, but warm after the El Chichón (17°N) eruption in 1982. Thus, over the one-year period following the eruptions, Northern Hemisphere surface temperature is indicated as cooling 0.34°C after Agung, but warming 0.37°C after El Chichón, a difference significant at the 0.5% level according to Student';s t-test. This difference in Northern Hemisphere temperature change is mainly due to differences in north temperate latitudes where, over the one-year period, the surface temperature is indicated as cooling 0.36°C after Agung but warming 1.27°C after El Chichón. It is proposed that the warming after El Chichón is mostly due to the anomalously warm sea surface temperature (SST) in the eastern equatorial Pacific (El Niño) in 1982–83, the relation between SST and tropospheric temperature being an obvious one in the tropics but of a more indirect nature in midlatitudes. The best evidence so far for a tropospheric cooling due to E... Abstract Tropospheric temperatures tended to cool after the Agung (8°S) eruption in 1963, but warm after the El Chichón (17°N) eruption in 1982. Thus, over the one-year period following the eruptions, Northern Hemisphere surface temperature is indicated as cooling 0.34°C after Agung, but warming 0.37°C after El Chichón, a difference significant at the 0.5% level according to Student';s t-test. This difference in Northern Hemisphere temperature change is mainly due to differences in north temperate latitudes where, over the one-year period, the surface temperature is indicated as cooling 0.36°C after Agung but warming 1.27°C after El Chichón. It is proposed that the warming after El Chichón is mostly due to the anomalously warm sea surface temperature (SST) in the eastern equatorial Pacific (El Niño) in 1982–83, the relation between SST and tropospheric temperature being an obvious one in the tropics but of a more indirect nature in midlatitudes. The best evidence so far for a tropospheric cooling due to E...