Bruno Peres / Agência BrasilFlooded streets in Eldorado do Sul, Rio Grande do Sul, in June 2024Bruno Peres / Agência Brasil
Three Brazilians in the USA and one in France spent months calculating the volume of rain that fell in Rio Grande do Sul, mostly in the Metropolitan Region of Porto Alegre, in May 2024. Iury Simoes-Sousa and Catarina Camargo, both from the Woods Hole Oceanographic Institution, Agata Piffer-Braga of the University of Massachusetts Dartmouth, and Juliana Tavora of the University of Twente in the Netherlands, combined several remote sensing methods with water level and precipitation data and interactive maps to estimate the rainfall volume at 1.5 billion cubic meters (m3). It is the equivalent to the floodgates of the Itaipu hydroelectric dam, which allow 62,200 m3 to pass every second, remaining open for almost seven hours, with all this water flooding the state capital and its surroundings. In May 2025, five weather stations recorded more than 380 millimeters of rainfall, almost four times the historical average since 1960. The result of a heat wave meeting a cold front, the intense and prolonged rainfall directly affected 420,000 people in the Metropolitan Region and caused 183 deaths (Geophysical Research Letters, February 21).
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