Given the increase in the frequency, intensity, and persistence of heat waves since the 1970s, and in view of the impacts that extreme temperatures may cause for society and the economy, this study aims to characterize heat waves in the subtropical region of Brazil and compare findings with the criterion defined by the World Meteorological Organization (WMO). Daily maximum temperature data was used. By using the percentile methodology, the subtropical region was divided into two regions: region 1 and region 2. We identified 54 heat waves in region 1 and 34 in region 2, which occurred more frequently in winter and spring, and less frequently in summer. A close relationship was observed between the Pacific Decadal Oscillation (PDO) and El Niño–Southern Oscillation (ENSO), both of which are able to modulate the heat waves in each of the different regions. Region 1 presented the highest number of heat waves during the warm (cold) phase of the PDO. As for ENSO, heat waves were more frequent in the neutral phase in both regions. Finally, there was shown to be an increase in the frequency and persistence of heat waves since the 1980s, especially in region 2. The methodology used in this study allows the identification and characterization of heat waves in several regions of different climates.

This study investigates a summer heat wave (HW) associated with downslope winds (DWs) affecting the central region of the state of Rio Grande do Sul (RS), Brazil. The temporal evolution of both phenomena is analyzed in the atmospheric boundary layer (ABL) using a combination of micrometeorological and rawinsonde data. For spatial characterization, ERA-5 reanalysis data are used. The HW covered a large area in southern Brazil, Argentina, and Paraguay. The main features of the HW were locally enhanced in the central region of RS by the development of DWs. The establishment of DWs near the surface depends on the dynamics of the ABL and local topographic features. The results showed that DWs that occurred during the HW contributed to the extreme temperatures and were associated with strong northerly winds, low relative humidity, and a drop in the dew points. Together, these extreme events influenced the turbulent and mean flow patterns of the ABL. The increase in turbulent activity associated with the warming of the ABL favored enhanced growth of morning ABL, while at night the simultaneous effects of radiative and turbulence cooling inhibited the formation of a strong stable ABL. The analysis highlights the complex interplay of synoptic and local factors associated with DWs and HW.

The Musaceae family is susceptible to Fusarium wilt (Fw), which is considered the most important disease globally, caused by a group of Fusarium species that includes F. oxysporum f. sp. cubense tropical race 4 (FocTR4). Until recently, FocTR4 was not present in Latin America. However, wilting, chlorosis of leaves, and vascular discoloration (typical symptoms of Fw) were observed in at least a hundred Cavendish plants located in Colombia, Peru and Venezuela in 2019, 2021 and 2022, respectively. Normally, the disease is more severe throughout the warmer and rainy months of the year. Since Ecuador is the world's leading exporter of bananas, including plantains, this study aimed to identify agroclimatic favorability zones for FocTR4 potential incidence in the country, testing linear models to evaluate disease occurrence in relation to climatic conditions and map favorability zones. Most of the banana-producing provinces, including Guayas, Los Ríos, El Oro, Manabí, Santa Elena, and Esmeraldas, presented an estimate ranging from medium-low to very high. In Guayas and Los Rios, the agroclimatic favorability zones of the main Ecuadorian producer provinces for a very high-risk account for almost 50%. This information can help make preventive management decisions in zones with a greater risk of spreading FocTR4.