I. Introduction
Previous years, dry and wet seasons in Indonesia, especially in Kemayoran Jakarta could be predicted by only using the calendar, but since the weather system is getting uncertain and can cause disadvantages of many fields, daily activities and many others, thus it is needed a system which can accurately predict the weather changes. In the previous research, it had been building a weather forecast system which used Artificial Neural Network (ANN) with the optimum of Conjugate Gradient, but the result from the research couldn't be used predict the rainfall because of the high Mean Absolute Percentage Error (MAPE) [1], [3]. On the other hands, the research on rainfall prediction using algorithm Evolving Neural Network (ENN) which has fully connected feedforward neural network [3], can predict the rainfall with MAPE as 38.82%. in this research, it is hoped that with the implementation of hybrid Genetic Algorithm (GA) and PCFNN which has partially connected feedforward neural network, enables us to produce a better rainfall prediction.