We examined associations between warm sea surface temperature (SST) anomalies and coral bleaching in the Gal¿pagos Islands and the Gulf of Panam¿, in the tropical eastern Pacific Ocean. Interannual SST variability is dominated by the El Ni¿o-Southern Oscillation phenomenon at Gal¿pagos, whereas only strong events have an SST signature in Panam¿. We explored various SST-related metrics potentially associated with bleaching occurrence: maximum absolute SST, SST anomaly, and the combined effect of intensity and duration of both SST anomalies (described via a degree days index) and high SST events. In Gal¿pagos, three Ni¿o years (1983, 1987, and 1992) coincided with bleaching. These were the top three years in both maximum annual SSTs and degree days values. In Panam¿, bleaching in 1983 coincided with high maximum SSTs and high degree days. In contrast, no bleaching was detected in 1972 despite high values of both quantities. We found all temperature-related metrics to be highly correlated, and it was impossible to isolate their effects.¿ 1997 American Geophysical Union