This paper presents a methodology based on a model proposed by Silva for the prediction of seasonal rainfall in Paraíba State, Brazil. Seventy-two rain-gauge stations were employed, all of them distributed in three mesoregions in Paraíba State. A rainy season (RS) with different subdivisions was established for each mesoregion. The Zi proportions – the ratio between the cumulative rainfall of the first RS period (Xi) and the rainfall of the whole RS - were made to fit the Beta probabilistic model used for calculating the first and fourth quintiles and the probability of rainfall above the climatologic average for the RS second period (Yi). The performance of the prognostic model for the period 1996-2000 was evaluated. In the period 1996 to 2000, with rainfall above Yi average, the margin of error was less than 20 %, except for the RS8 in 2000. In 1998 - a very dry year - the margin of error was over 20 %, this for the prognostic of a minimal total rainfall. The methodology adopted proved be very accurate for forecasting droughts in Paraíba State.