The question is raised whether rainfall over the sugar and pineapple plantations in the central parts of the island of Oahu in the Hawaiian group is so sporadic and disorganized that it is not amenable to short term forecasting, or whether it occurs in sufficiently organized form so that general synoptic forecasts for Hawaii can be supplied that will be useful for operations on the plantations. It turns out that most rainfall is attributable to synoptic disturbances. This is more true in winter, when the islands normally experience their heaviest rainfall, than in summer, when precipitation is at its seasonal low ebb. Further analysis of the disturbances shows that a few large storms produce over ⅔ of the annual rainfall total and that the orographic effect responsible for local differences in rainfall received from storms decreases in importance as storm intensity increases.