The Rio Guaíba in Porto Alegre, Brazil, reached flood levels at the Cais Mauá area on June 25, 2025, prompting the Rio Grande do Sul Civil Defense to provide technical guidance to municipal coordinators for contingency measures. In response to the rising water levels and flood risk, the Porto Alegre city government initiated the closure of four flood protection gates (comportas 1, 2, 4, and 6) located at Cais Mauá during the early hours of June 30. This action was taken to reinforce flood defenses amid continued heavy rainfall in the region. By July 3, the water level of the Guaíba receded, allowing the city to begin reopening the previously closed gates, with authorities confirming it was safe to do so. The reopening process continued into July 4, coinciding with reports of fog affecting operations at Porto Alegre's Salgado Filho Airport. The city’s flood management efforts reflect ongoing monitoring and response to fluctuating water levels in the Guaíba amid seasonal rains.