The seasonal cycle of water storage of each of the 70 major river basins of the world is evaluated by means of basin-atmosphere water budgets. The atmospheric data of National Centers for Environmental Prediction (NCEP) Reanalysis is used together with river runoff data. In the tropics and in the temperate zone of East Asia, storage becomes largest at the end of the rainy season and smallest at the beginning of the rainy season. In the cold region and in the temperate zone of North America, storage becomes largest in spring and smallest in summer or autumn. The global sum of storage becomes largest in spring of the northern hemisphere, when the contribution of the northern cold region and the southern tropics coincide. ¿ 2001 American Geophysical Union