Abstract— In recent decades, climate index has become an important tool in hydrological studies. Accordingly, the implication of climate change in hydrological researches requires the assessment of historical and future climate characteristics to understand current and future processes for water resources management improvement. The aim of this study is to analyze historical rainfall anomalies over the Mouhoun watershed by applying precintcon package in R studio. Required data for the assessment of the rainfall anomalies was retrieved from the National Meteorological Agency (NMA) of Burkina Faso. Purposely, monthly rainfall data of three meteorological stations spanning from 1980 to 2012 were collected. The findings revealed that within Mouhoun watershed, the rainfall data are leptokurtic and the distribution is narrower than normal. This result shows thus a moderate dry rainfall anomaly. During the second period of analysis (1990-1994), The station of Bobo Dioulasso is showing an estimated value of -2.594. This value of the RAI is indicating a slightly dry pattern of rainfall in this station. However, the stations of Boromo, is presenting a value of RAI in the range of -1. 00 to -1.99 highlighting a moderate dry rainfall characteristic. During the period (1995-1999), slightly dry conditions are detected in Bobo and Boromo. From 2000 to 2004 and 2005 to 2011, moderate dry RAI index is identified for all station except for the station of Gaoua. Among these six stations of the watershed, Gaoua station which is located in the southwestern part of the watershed has experienced throughout the period of analysis a dryness conditions. Indeed, a slightly dry rainfall anomaly is detected with a RAI ranging from -0.50 to -0.99. The results obtained could serve as a guide to decision makers in water and climatic management.