The upper ocean salinity balance in the western equatorial Pacific warm pool was evaluated using up to 2.5 years of data (September 1991 through April 1994) from the Coupled Ocean-Atmosphere Response Experiment's enhanced monitoring array of moorings. At the central mooring site (0¿, 156 ¿E), precipitation had a record-length mean of 4.5 m yr-1, while evaporation had a mean of 1.4 m yr-1. This excess surface freshwater flux was balanced primarily by vertical mixing (estimated as the residual of a salt budget calculation) and by zonal advection. For timescales between a month and 2.5 years, surface salinity variability was dominated by zonal advection and only weakly correlated with precipitation, consistent with the concept of a zonally migrating fresh pool. The effects of precipitation on local surface salinity variations were more apparent for timescales shorter than a month. Shallow rain puddles tended to form in a matter of hours. However, owing to the combination of mixing and advection, these precipitation-generated freshwater puddles were typically short-lived. ¿ 1998 American Geophysical Union