For many years, rainfall has been measured in Brazil on a daily basis only; hence it is unusual to find studies considering a better temporal resolution for the whole country. However, since 2013, the National Centre for Monitoring and Early Warning of Natural Disasters (CEMADEN) has started to monitor rainfall in a sub hourly basis at more than 3,000 gauges. This study is the first to analyze sub-daily characteristics of rainfall in Brazil on national scale. Raw data from 3 years (2015-2017) was downloaded from CEMADEN’s home page and then quality control procedures were applied to select the high-quality rain gauges. Then, two rainfall properties were calculated: (i) Number of Wet Days – NWD, which is the number of rainy days per year; and (ii) Number of Effective Wet Days – NEWD, which is the number of rainy hours per year divided by 24 hours. Both NWD and NEWD were grouped according to NEWD values and spatially analyzed. About 1,100 rain gauges were used in this study: 824 (2015), 1,288 (2016), and 1,385 (2017). NWD ranges from 26 to 226 days (average: 151 days), while NEWD ranges from 1.2 to 47.8 days (average: 14.3 days). Results showed that group A (NEWD < 10.3 days) contains gauges located in the Brazilian Mid-western and northeastern semiarid regions. Group B (10.3 ≤ NEWD < 13.2 days) occurs in parts of the coastal region of Northeast and highlands of Southeast. Groups C (13.2 ≤ NEWD < 17.4 days) and D (NEWD ≥17.45 days) are found in South and part of the Southeastern coastal region. The region with the most concentrated rainfall rates (group A) is the one with the lowest annual rainfall. Orographic effects seem to cause reduction in NEWD, from 15.2 days to 11.8 days (group B). Groups C and D comprehend the rainiest region, preceded by the Amazon region. Finally, we highlight that spatial distribution of NWD and NEWD did not change abruptly annually, with an overall ratio between them of ~10 times. Although in some regions rainfall occurs in four months, it effectively falls from 10 to 13 days. This study is important to understand how concentrated the rainfall is in the different Brazilian regions.