A powerful extratropical cyclone and its associated cold front have brought destructive winds, severe thunderstorms and widespread disruption across southern and southeastern Brazil.
Rio Grande do Sul suffered the most extensive damage, with a confirmed tornado, wind gusts reaching 134.3 km/h (83.5 mph) and impacts reported in at least 114 municipalities. One person was killed, five were injured and more than 2,300 residents were forced from their homes.
As the cyclone moved southeast over the South Atlantic, strong winds spread along the coast through Santa Catarina, Paraná, São Paulo, Rio de Janeiro and Espírito Santo.
#Ahora ⚠️🌪
— Tiempo AMBA (@Tiempo_AMBA) August 6, 2026
Tornado en Rio Grande do Sul (Sudeste de Brasil, a 100km de Uruguay).
La zona se encuentra bajo alerta por fenomenos significativos.@SergioJalfin @MeteoNacho pic.twitter.com/BuzWKnAhne
Why did the cyclone become so powerful?
The system began developing from an elongated area of low pressure over northern Argentina and Paraguay. A surface low subsequently formed between Uruguay and the coast of Rio Grande do Sul.
According to Brazil’s National Institute of Meteorology, known as INMET, forecasts showed the cyclone’s central pressure potentially falling by around 26 hPa in 24 hours.
This rapid strengthening process is known as explosive cyclogenesis or bombogenesis. As the central pressure falls, the difference in pressure between the cyclone and surrounding areas increases, causing winds to accelerate over a wide area.
The cyclone remained offshore, but its large circulation intensified a cold front crossing southern Brazil. Warm, humid air ahead of the front combined with strong wind shear to create an environment favourable for damaging thunderstorms, hail and isolated tornadoes.
Tornado confirmed in Pedro Osório
Rio Grande do Sul’s Civil Defence confirmed that a tornado touched down in a rural area of Pedro Osório on Thursday, August 6.
The tornado developed from a supercell, an organised thunderstorm with a persistent rotating updraft. Damage was reported near the rural community of Matarazzo, although no tornado-related injuries were confirmed.
This was the second consecutive week with a confirmed tornado in Rio Grande do Sul. Another tornado affected areas around Giruá, Sete de Setembro and Senador Salgado Filho on July 28.
The strongest measured gust reached 134.3 km/h (83.5 mph) at General Câmara. Porto Alegre recorded 120.4 km/h (74.8 mph), while winds reached 113 km/h (70 mph) in Canoas.
Another day, another Tornado in Brazil. Today, in Pedro Osorio – RS pic.twitter.com/CI8wUKP4LP
— Lucas Moura (@lucaschaser) August 6, 2026
A motorcyclist died in Montenegro after being struck by a falling tree. Five people were injured across Dom Feliciano, Novo Hamburgo and Osório.
Civil Defence reported 2,306 displaced residents. Novo Hamburgo recorded 480, Sapiranga 360 and São Leopoldo 200. Nova Hartz and Portão each reported 180.
Caseiros reported damage to 140 homes, while more than 100 properties were affected in Santa Cruz do Sul. Schools, a hospital, a prison wall and other public buildings were also damaged.
At the height of the storm, approximately 250,000 customers lost electricity. That number had fallen to around 45,000 by Friday evening.
Rio de Janeiro issues extreme wind alert
As the cyclone moved farther offshore, its strongest winds expanded northward along Brazil’s southeastern coast.
INMET issued coastal wind warnings covering Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Rio de Janeiro and Espírito Santo, with some alerts remaining in force through Saturday evening.
Rio de Janeiro state declared optional attendance for state employees from 1 p.m. on Friday. Residents of the capital received an “extreme alert” on their mobile phones at around 12:35 p.m., warning of severe storms and strong winds and advising people to return home early.
Rio briefly reached Alert Stage 3 before returning to Stage 2 as winds weakened. Civil Defence recorded 22 wind-related incidents, mostly involving fallen trees, with no injuries reported.
A gust of 88.7 km/h (55 mph) was recorded at Praia do Abraão in Angra dos Reis. Galeão Airport recorded 66.6 km/h (41 mph), while Paraty reached 74.5 km/h (46 mph).
Public schools and universities cancelled activities, parks closed and tourist transport to Christ the Redeemer was suspended.
Port of Santos closes to navigation
The cyclone also generated damaging winds along the São Paulo coast. Santos recorded a gust of 109 km/h (68 mph) at 7 a.m. on Friday, bringing down large trees.
The Port Authority closed the Port of Santos navigation channel at 6:45 a.m. because conditions were unsafe. Ferry crossings connecting Santos with Vicente de Carvalho and Guarujá were also suspended, although services resumed at 7:25 a.m.
Schools were closed as a precaution in Bertioga, Itanhaém, Peruíbe and Ubatuba. Authorities advised residents to avoid the sea and maritime transport during the dangerous conditions.
The cyclone is now moving southeast away from South America, but strong coastal winds may continue while its circulation remains close enough to influence Brazil.
Behind the cold front, a powerful mass of cold air is spreading across southern Brazil. Temperatures may approach 0°C (32°F) in parts of Rio Grande do Sul, with frost possible across the state, Santa Catarina and Paraná.
