We analyse seasonal and annual trends of extreme indices of air temperature and precipitation over Brazil during the period 1961–2018. The main goal is to investigate whether the climate is changing and if so, to explore if there is any marked seasonality in such changes. The daily observed datasets of maximum and minimum temperatures, and precipitation, are provided by the Brazilian National Institute of Meteorology and National Water Agency. We use the Sen Curvature and Mann‐Kendall statistical tests to compute the magnitudes and to evaluate the statistical significance of climate extremes trends, respectively. The results show that the warm extremes frequency of occurrence is increasing significantly while the opposite occurs for cold extremes, which reveals a very consistent and widespread warming over Brazil. The highest increases in warm extremes occur during austral spring and summer while for the cold extremes the greatest decreases are observed during austral winter. Unlike temperature, precipitation extremes show heterogeneous signals for most of the country. In Northeast Brazil, there are changes towards a drier climate, especially in summer and autumn. In the Southern region, the climate is becoming wetter, with a reduction in consecutive dry days, especially in spring. For the other regions, there is no strong clear change sign, but both positive and negative precipitation extreme trends, without statistical significance (mostly in Southeast Region).

The continuous understanding of extreme weather events in the Amazon is fundamental due to the importance of this biome for the regional and planetary climate system. Climate characterization and the identification of changes in the current climate can be key findings for adaptation and mitigation measures. This study examined climatology and trends in 20 climate extreme indices associated with air temperature and precipitation in the Brazilian Legal Amazon (BLA). Daily observed data, interpolated at grid points, were analyzed from 1961 to 2020. Statistical tests were employed to determine the trend’s significance and magnitude. The results indicate that prolonged heat, hot days, and annual temperature records have become increasingly frequent in practically all of BLA over the last decades. Warm days and nights are increasing at approximately +11 days/decade. Heat waves have gone from 10 to 20 consecutive days on average in the 1960s to around 30–40 days in recent years. Indices associated with the intensity and frequency of extreme precipitation show a reduction, especially in the rainiest portion of the BLA, the western sector. In the east/south region of BLA, where consecutive dry days reach 100 days/year, they continue to increase at a rate of +1.5 days/decade, a fact related to the delay at the beginning of the rainy season. These aspects deserve attention since they impact local circulation, reducing the convergence of humidity not only over the BLA but also in central-southern region of Brazil.

This study aims to investigate the projections of air temperature and precipitation climate extremes in the Brazilian Legal Amazon (BLA) through the end of the century. The Brazilian Daily Weather Gridded Data dataset is used to characterise the present climate, and 12 models from the Coupled Model Intercomparison Project Phase 6 (CMIP6), under the Shared Socioeconomic Pathways scenario SSP5-8.5, are employed to assess future changes relative to the reference period (1995–2014). Student’s t-test is employed to evaluate the robustness of the projected changes. Results show that warming is projected to persist throughout the BLA, but at a lower rate in the north-east (NE) than in other areas. In the south (S) and north-western (NW) sectors, the highest maximum temperatures will increase by an average of 7°C by the end of the century. Regarding precipitation extremes, in the NW, which is currently the wettest portion of the BLA, models project a reduction in consecutive wet days (CWDs) and an increase in the amount of daily rainfall that exceeds the 95th percentile of wet days (R95p). In the NE, by the end of the century, a 30-day increase in the total number of consecutive dry days per year (CDDs) is projected, combined with a reduction in annual rainfall of ~270 mm. In the south of the BLA, models project an increase across the entire sector, with an additional 15 days per year, along with a reduction in annual rainfall. The projected changes in precipitation exhibit strong seasonality, concentrating primarily in the transitional seasons and the beginning of the rainy season, rather than occurring uniformly throughout the year. Also, the projected warming intensifies during the dry season and austral spring, especially in the NW region. In this sense, it is observed that, in the future, the climate in the BLA will become warmer, keeping the trends observed in the present climate, as shown in other previous studies. However, rainfall patterns differ between regions: while in the NE and S the climate will become drier, in the NW, the intensity of extreme rainfall is expected to increase significantly by the end of the century.

This article is a case study to analyze the synoptic and climatological aspects of an heat wave in Rio de Janeiro, located in the Southeast Region of Brazil, during November 2023. This work aims to investigate whether the high temperatures recorded on November 17 and 18, 2023, during a concert of an American singer, could be considered an extreme weather event. On the first day of the concert, the 17th, many people fell ill due to the extreme heat, and a 23-year-old female died, a victim of cardiorespiratory arrest caused by thermal exhaustion. On November 18, 11 meteorological stations recorded a maximum temperature (TX) equal to or over 40 °C, and the highest TX in the city was 43.5 °C. At a station located in the coldest area of the city, the highest TX (39.6ºC) in its entire historical record (1967-2023) was also recorded on the 18th. Such extremely high temperatures occurred during a prefrontal situation and at the end of a heat wave that lasted eight days. Analysis of the diurnal cycle of the air temperature on the 17th and 18th indicated that the minimum temperature (TN) was about 5 to 6 °C above its climatology; the TX was approximately 13 °C above its climatological value, and high temperatures lasted all afternoon. On the 18th, the Heat Index reached 55.1 ºC at 14:00 and 15:00 LT, characterizing a state of medical emergency during seven hours. In terms of climate, in addition to the increase in intensity and frequency of warm extremes over the city, the El Niño phenomenon (EN) was configured in the Pacific Ocean from April 2023 to May 2024, causing a drier and warmer spring in Southeast Brazil. This concert represented a milestone for the city regarding the need for local public policies to regulate massive crowd-gathering events during heat wave episodes. Finally, it is possible to state that the event was extreme, caused by the combination of a heat wave, in a prefrontal situation, during an EN event, and in a context of climate change.