Extreme weather events linked to El Niño have knocked down more than 290 power transmission towers across Brazil since late July, most of them in the South region and some in the Northeast, according to the ONS, the agency that operates the country's national power grid. The figures were presented on Wednesday (21) in Rio de Janeiro by the agency's board, which expects storms to get worse in the coming months, as reported by Folha de S.Paulo.
ONS operations director Valter Cardeal said 191 towers on 230 kV and 500 kV lines fell between July 26 and Wednesday, plus more than one hundred 138 kV structures. According to the agency's director-general, Márcio Rea, the towers now in service were not designed for current wind speeds: "In the past, a heavy rainstorm brought winds of 90 to 100 kilometers per hour. Today they reach 250 km/h," he said. Rea described the phenomenon as air currents that descend in opposite directions and collide near the ground: "It is like an explosion. It even twists the towers."
Rio Grande do Sul at the epicenter
The most severe case hit the far south of Rio Grande do Sul state. On August 6, an extratropical cyclone brought down towers on the high-voltage line that supplies Santa Vitória do Palmar and Chuí, on the shores of the Mirim Lagoon; two of them fell into the lagoon itself. More than 60 workers were mobilized for the rebuilding, and utility CEEE Equatorial said the storm hit about 34 of the 72 municipalities in its concession area, with gusts up to 132 km/h. In August, Cardeal had already told Valor Econômico that the collapse of around 20 towers in Chuí left the region without power for five days and blocked local wind farms from delivering their output.
The problem goes beyond that single episode. According to the ONS, Brazil is facing a frequency of tornadoes and extratropical cyclones not seen before: eight tornadoes have been recorded this year in Paraná state alone, and the agency says it has "lost count" of those in Rio Grande do Sul and Santa Catarina. The national transmission network spans about 186,000 kilometers, and older towers were designed for winds up to 160 km/h, Cardeal said at an industry workshop in August. Rea told Folha he asked tower manufacturers about reinforcing the structures, but the answer was that it would take nine times more steel, at a prohibitive cost. "That is not the way to go," he said.
What is being done
With no immediate structural fix, the ONS has been sending storm forecasts to transmission companies so they can keep crews on alert. Cardeal argues the system has absorbed the impacts: "The system is resilient, the load shedding was very small, I would say insignificant." In August, ONS board chair Solange Ribeiro told Valor the sector needs closer cooperation between companies, Civil Defense and distribution utilities, plus investment in more resilient networks recognized in power tariffs: "Investments designed for the climate of the past, alone, will not solve the problems of the future."
The same rains that topple towers have, on the other hand, filled the reservoirs of Brazil's hydro-dependent grid at the start of the rainy season. According to the Ministry of Mines and Energy, reservoirs in the national interconnected system ended September at 61% of capacity, against 56% in the same month of 2025. The ONS projects 56.7% by the end of October, with the South reaching 88.2%, where water flowing into the dams is at 228% of the historical average. As a result, thermal plants, which generate more expensive power and are switched on when hydro reservoirs run low, should be needed only at peak consumption hours. "The water tank is full," Rea said, with one caveat: forecasts point to even stronger storms in the coming months.