Rio de Janeiro issues maximum alert and bans swimming as strong El Niño drives unsafe beach water

The Rio de Janeiro municipal government placed the city in "maximum alert" and activated summer‑time emergency protocols weeks ahead of schedule because meteorologists forecast a very strong El Niño with an 81 % chance of intensifying heat and heavy rain through the upcoming months. More than 50 municipal agencies were mobilised, with the Centre of Operations and Resilience monitoring sirens, pluviometers, radars and flood‑control measures, while accelerating drainage works across vulnerable neighbourhoods.

Concurrent water‑quality monitoring by the state environmental agency (Inea) showed that 20 sections of the Zona Sul coastline were classified as unsuitable for swimming after recent cold fronts and intense rains increased bacterial contamination. Only three small sections – a stretch of São Conrado, Praia Vermelha and an area of Praia do Leme – remained safe. Inea advised the public to avoid sea contact for at least 24 hours after heavy rainfall.

The city also recorded stable, hot weather for the coming days, with temperatures above 30 °C and low humidity, before a cold front is expected later in the week. Similar preparation efforts were reported in Pato Branco, Paraná, where the municipal contingency plan was updated and an El Niño monitoring committee was established to coordinate response to extreme weather events.