The aim of this study was to understand the distribution of rainfall in the monthly and seasonal scales of the river basins of Ribeirão Santo Antônio and José Manuel, located in the state of Goiás. Rainfall data were made available through the National Water Agency (ANA) , through the hydroweb system (2015). Rain data were downloaded from 4 stations near the study area, from 1974 to 2016. The data were tabulated in the Excel program, extracting the monthly average of the analyzed historical series. The results obtained by the monthly analysis of the whole historical series showed that the months of January and December were the ones that presented the highest rainfall averages, with values recorded above 250mm, except for the Montividiu / GO station, which recorded an average below 240mm for the entire series. With this, it can be concluded that the months with the lowest values were May, June, July and August, obtaining a monthly average of minus 30mm for the historical series. For the seasonal scale of the study area, summer was characterized as the season with higher rainfall indexes and winter the driest season.
