Porto Alegre, the capital of Rio Grande do Sul, has officially become the hottest city in Brazil, reporting record-breaking temperatures this week as the southern region faces intense heat due to persistent weather patterns. According to the Instituto Nacional de Meteorologia (INMET), the temperature in Porto Alegre reached 37.9°C on February 10, 2025, surpassing the previous record of 37.6°C set just days earlier on February 4, 2025.
This staggering rise has not only set new temperature records but has placed Porto Alegre above traditionally hotter cities such as Rio de Janeiro, which reached 35.5°C, and Cuiabá, which hit 34°C. Other cities across Rio Grande do Sul also reported extreme highs, with Uruguaiana soaring to 40.4°C and Santiago to 40.1°C.
According to meteorologists, the unparalleled heatwave affecting the area is primarily caused by a concentrated mass of hot, dry air lodged firmly over the southern part of Brazil. This situation suppresses cloud formation, leading to incredibly high temperatures and limited precipitation, which has dramatically reduced humidity levels to alarming lows.
"The absorption of heat from surfaces like asphalt leads to higher temperatures, which can result in health issues," said Paulo Brack, a professor at the Universidade Federal do Rio Grande do Sul (UFRGS) and member of the Instituto Gaúcho de Estudos Ambientais (INGÁ). His insights highlight the challenge posed by urbanization, where the proliferation of concrete has contributed to the phenomenon known as urban heat islands.
Local parks, typically populated by families seeking refuge from the heat, appear deserted. Popular destinations, such as the Orla do Guaíba and Parque Marinha do Brasil, are significantly less crowded than usual, as residents heed warnings about the extreme weather.
Given the extreme temperatures, the State Health Department has issued urgent advisories, urging citizens to take precautions against the heat. Dehydration, headaches, and increased risks of heat exhaustion are just some of the potential health impacts highlighted by health officials. People are advised to increase their water intake, avoid strenuous outdoor activities during peak heat hours, and seek shade whenever possible.
Despite these warnings, the heat's impact has created significant disruptions, particularly within the education sector. The Cpers-Sindicato, representing over 80,000 state educators, secured a temporary court ruling to postpone the start of the school year, citing serious health risks for both students and teachers. This decision has led to tensions between union representatives and government officials, who argue about the availability of air conditioning facilities within schools.
"We've seen incredible spikes of temperature, with thermometers even registering over 62°C on exposed surfaces at parks," noted Brack, who also emphasizes the importance of vegetation in moderative temperatures. According to him, neglecting urban greenery can exacerbate health issues, particularly amid extreme heat conditions.
Most concerning is the fact Porto Alegre is merely the tip of the iceberg; as the heatwave encapsulates southern Brazil, meteorologists are predicting continued heat over the upcoming days, warning residents to brace for additional discomfort. "The heat expects to persist, and conditions are predicted to worsen before alleviation through upcoming rainfall," stated Climatempo’s reports.
The territorial impact extends beyond Porto Alegre. The southeastern part of Brazil—including states like Mato Grosso do Sul—is grappling with similarly oppressive heat levels. Cities here registered temperatures around 37°C as well.
With the unprecedented levels of heat, Brazilians face urgent questions about climate resilience. The effects of climate change, exacerbated by urban development practices, are starkly evident as these patterns push records to never-seen-before levels—it serves as both wake-up call and pivotal opportunity for long-term regulatory changes.
More measures will be needed to address the problem: revisiting city planning to increase urban greenery, improving water management systems, and fortifying services to assist those most vulnerable, lest record-breaking days become the norm.
Porto Alegre serves not just as the capital of one of Brazil’s southern states but, increasingly, as the litmus test for urban heat challenges amplified by climate factors. With conditions worsening, residents hope for rain and respite, eagerly awaiting the necessary evolution toward greener, cooler urban settings.