This paper addresses a methodology for analyzing spatio-temporal rainfall variability as a tool to support action planning that could mitigate negative impacts and reduce conflicts over water use in the Pajeú river basin, located in the semi-arid region of the state of Pernambuco. We used daily rainfall data from 11 rainfall stations, between 1964 and 2016, provided by the Pernambuco Water and Climate Agency (Agência Pernambucana de Águas e Clima — APAC) and the National Water Agency (Agência Nacional de Águas — ANA). This analysis employed the RClimDex software to calculate rainfallrelated climate extremes indices, aiming at monitoring and detecting climate changes and alterations in the regional rainfall pattern. The results indicated a change in the rainfall pattern in the Pajeú river basin, and all climate indices obtained converge toward the increase in water scarcity in the area, contributing to the recurrent droughts that impact the region.