A very simple statistical model is proposed to describe the time distribution of rainfall within a rainy event. The modeled process is the dimensionless hyetograph H(tj) that represents the fraction of rainfall accumulated over the time interval (0,tj), where tj is a fraction of the total duration. In any rainy episode lasting n+1 units of time, the sequence H(tj),...,H(tn) is described as an ordered sample from the beta distribution. Dimensionless rainfall from hourly data at three stations in Southern Spain show little dependence on rainfall duration, amount of precipitation, or period of the year. These results, though not essential to the model structure, simplify its formation, reducing the number of parameters. Other features of the historical records, such as correlations, maximum dimensionless hourly precipitation, or frequency curves, are reasonably well reproduced by the model. ¿ American Geophysical Union 1993