Cacao is a typical plant of a tropical climate and demands ample water. Thus, in periods of water deficit, the need for supplementary irrigation can influence crop development. This study aimed to characterize the climate and evaluate the need for supplementary irrigation for cacao crops in the south of the state of Bahia (Brazil). For this research, historical data (2001-2017) for climate variables were obtained that are available at the weather station of the Executive Commission for Cacao Cultivation Planning (CEPLAC), located in southern Bahia. With the complete database, the monthly values for each variable were calculated and subjected to descriptive statistical analyses. Subsequently, the mean values for rainfall and air temperature were used to calculate potential evapotranspiration. The climatological water balance was then calculated, defining the periods of water deficit and surplus and whether supplementary irrigation was necessary or not, based on the total monthly water deficit. Overall, the region had a favorable climate for the development of cacao. However, this pattern did not continue throughout the historical series of climatic data, which showed temporal discontinuity, especially in February. The main months requiring supplementary irrigation for the cultivation of c hern Bahia were February and December.