River basins are important territorial units for geographical analysis, and are crucial for environmental planning, especially in metropolitan settings. The aim of this article was to evaluate rainfall trends and variability in the Guapimirim-Macacu basin, located in an urban development area in the Rio de Janeiro Metropolitan Region. Annual, monthly and daily records were collected from twenty rain gauge stations, for the period of 1967 to 2015. Analyses conducted using the RClimDex software revealed an increase in rainfall volume and number of wet days. The remaining indicators and patterns observed across stations also suggested that changes in precipitation trends occurred mostly on the day scale, and were likely attributable to global climate change. After controlling for seasonality and normalizing the series, a linear tendency between the mean monthly precipitation in the Guapimirim-Macau basin and sea surface temperature (SST), obtained from the National Centers for Environmental Prediction, revealed that rainfall in the region is strongly correlated with Pacific and Atlantic SST, revealing the importance of the South Atlantic Convergence Zone for rainfall variability in the area of study, especially in summer. These data are important for development planning and the management of water resources and supply in the Rio de Janeiro Metropolitan Region.

流域是进行地理分析的重要地区单位，对于环境规划至关重要，特别是在大都市环境中。本文的目的是评估位于里约热内卢大都市区城市开发区的Guapimirim-Macacu盆地的降雨趋势和变异性。从1967年到2015年期间，从二十个雨量计站收集了年度，每月和每日记录。使用RClimDex软件进行的分析显示，降雨量和湿天数增加。各地观测到的其余指标和模式也表明，降水趋势的变化主要发生在日尺度上，很可能归因于全球气候变化。在控制季节性并标准化序列后，从国家环境预测中心获得的Guapimirim-Macau盆地平均月降水量与海表温度（SST）之间的线性趋势表明，该地区的降雨与太平洋和大西洋SST密切相关，这表明了研究区域（尤其是夏季）降雨变化的南大西洋收敛带。这些数据对于里约热内卢都会区的发展规划以及水资源和供应的管理非常重要。揭示了南大西洋收敛带对于研究区域（尤其是夏季）降雨变化的重要性。这些数据对于里约热内卢都会区的发展规划以及水资源和供应的管理非常重要。揭示了南大西洋收敛带对于研究区域（尤其是夏季）降雨变化的重要性。这些数据对于里约热内卢都会区的发展规划以及水资源和供应的管理非常重要。