Rainfall is one of the most important climatic elements when it comes to characterising the climate and human activities, which is why it is necessary to understand both its chronological and spatial evolution. The spatial and temporal distribution of rainfall in the Amazon region has been the subject of several studies, which have shown the importance of rainfall in the region. Although rainfall analyses for the Belém region, which is characterised by high rainfall and no dry season, have been carried out in recent years, there is a lack of studies for this region. The city of Belém, capital of the state of Pará, is known as the city where it rains practically every day and almost on schedule (at 3pm). The traditional question in the city is: 'Are you going out before or after the rain?'. Those who don't know it may be startled, but it's quite common in the region. Therefore, this book presents unpublished information on the behaviour of rainfall on an hourly time scale and quantifies the importance of Belém do Pará's 'famous afternoon rain' in the average monthly rainfall total.