Annual rainfall is uncorrelated in time, at both sites. Both approaches yield very similar pdfs when using all data available. In Concepcion, totalising rainfall every 12 h results in a pdf that is undistinguishable from that obtained for continuous data, but aggregating over 24 h introduces bias. In Lugano, any level of aggregation introduces a bias. The proposed method is a much more consistent way of estimating the pdf of annual rainfall when only a few years of data are available, allowing for a robust estimation even for records as short as 5 years. Thus, derived distributions are a powerful tool for describing interannual variability in rainfall, in the case of short records or when climate might be nonstationary.