On May 6, 2025, the Defesa Civil do Rio Grande do Sul issued urgent hydrological and meteorological alerts for several regions, particularly emphasizing the southern half of the state. This area is expected to experience significant rainfall between Wednesday, May 7, and Friday, May 9, with accumulated precipitation projected to range from 140 to 200 millimeters. The alerts are categorized into two levels: orange, indicating a risk of strong and potentially damaging rain, and yellow, which signals attention for moderate to strong rain.
Regions under orange alert include Oeste, Missões, Campanha, Centro, and Litoral Médio, alongside Zona Sul. Meanwhile, areas designated with a yellow alert encompass Extremo Sul, the Região Metropolitana de Porto Alegre, Vales, Serra, Nordeste, and Norte. Meteorologist Henrique Repinaldo from the Centro de Pesquisas e Previsões Meteorológicas (CPPMet) noted that the heaviest rainfall is anticipated to concentrate in Oeste and part of Campanha starting tomorrow, May 7.
Initially, rainfall in the southern region may be more isolated, but conditions are expected to shift on Thursday and Friday, with a heightened potential for heavy rain. Meteorological models suggest that nearly 100 millimeters of rain could accumulate between Thursday night and Friday morning, raising concerns about urban flooding. "One of the concerns is the possibility of heavy rain both in volume over the two days and the potential for a larger amount to fall in a short period," Repinaldo emphasized.
Additionally, isolated storms with wind gusts exceeding 50 km/h and the possibility of hail are forecasted. The Mirim-São Gonçalo and Rio Camaquã basins are particularly highlighted in the alert scenario due to expected higher rainfall totals. Despite the current levels of major rivers in Rio Grande do Sul remaining within normal or below-average ranges, the anticipated rainfall could lead to elevated water levels in smaller bodies of water and localized flooding in urban areas, especially during and shortly after the most intense downpours.
As a precaution, the city hall is mobilizing various secretariats to monitor rainfall and water sources actively. One of their goals is to clear 2,000 storm drains in six months, focusing primarily on the central area. Pumping stations are under 24-hour surveillance to ensure their operation and cleanliness. The city has reportedly improved its preparedness, with teams ready to respond to any rain-related incidents.
In a separate development, the Civil Defense of Rio Grande do Sul issued two additional alerts for heavy rains on May 5, 2025, valid until 19:00. These alerts indicated risks of heavy rain, lightning, and hail. The first alert was released at 15:35, followed by a second at 16:30, which reiterated the forecast and extended its validity for three more hours. Residents were advised to adhere to local contingency plan protocols, avoid risky areas, and remain vigilant regarding landslides, floods, and potential power outages.
Emergency contact numbers were provided for residents, including Civil Defense at 199, Fire Department at 193, and Military Police at 190. The Defesa Civil stressed the importance of staying informed and prepared as weather conditions evolve.
As the situation develops, authorities are urging residents to keep an eye on official updates and take necessary precautions to ensure their safety. The combination of expected heavy rainfall and existing vulnerabilities in infrastructure could lead to challenging conditions in the coming days.
