Daily (1--2 day interval) reconstruction of sea water temperature is calculated via a freezing microtome sampling technique for oxygen isotope analysis and by counting the daily growth lines in a modern Tridacna (Hippopus hippopus, LINNE, 1758) shell collected from Ishigaki Island, Japan. This method enables the first direct comparison between shell oxygen isotopic values and daily meteorological data. The H. hippopus shell calcifies mainly under isotopic equilibrium with surrounding sea water. The high-resolution profile of Δ18O of the H. hippopus shell was recorded monthly to seasonal sea surface temperature variations of the local coral reef environment. ¿ 1999 American Geophysical Union