Brazil is largely outside the typical hurricane belts, and the South Atlantic Ocean rarely sees storms of hurricane strength, but the region is not entirely immune to tropical cyclone activity. The common understanding that the South Atlantic is completely free of these storms has been challenged by modern satellite observation and the occurrence of several documented events near the Brazilian coast. When the conditions necessary for intense storm development do align, the resulting weather can pose a significant and unexpected threat to the coastline.
The Rarity of Strong Tropical Cyclones Near Brazil
The South Atlantic basin is conspicuously devoid of tropical cyclones compared to the North Atlantic, the Northeast Pacific, and other active ocean regions. The term “hurricane” is generally inaccurate for storms near Brazil, as it is specifically designated for intense tropical cyclones occurring in the North Atlantic and Northeast Pacific Oceans. Storms in the South Atlantic are properly classified as tropical or subtropical cyclones, depending on their structure and formation.
The South Atlantic does not have a distinct, regular season like the North Atlantic. Instead, the small number of systems that do form tend to appear during the warmer months, typically between November and May, aligning with the Southern Hemisphere’s summer. The Brazilian Navy Hydrographic Center (BNHC) began assigning names to tropical and subtropical systems in the western part of the basin in 2011 when sustained wind speeds reach a minimum of 40 miles per hour (65 km/h). Before the satellite era, which began around 1970, the scarcity of records led many meteorologists to believe tropical cyclones simply could not form in this basin.
Meteorological Factors Inhibiting South Atlantic Storms
The general absence of strong tropical cyclones near Brazil is due to a combination of three major atmospheric and oceanic inhibitors. Tropical cyclones require sea surface temperatures (SST) of at least 79°F (26°C) to form and sustain themselves. However, the warm waters off Brazil do not extend far enough south to consistently fuel development, and overall, the South Atlantic SSTs are generally cooler than those in the North Atlantic.
A primary inhibitor is the consistently high level of vertical wind shear in the troposphere over the South Atlantic. Wind shear, which is the change in wind speed or direction with height, tears apart the vertical structure of developing storms. This prevents the organization of thunderstorms around a central low-pressure area, and low wind shear is a prerequisite for a storm to become a strong, organized tropical cyclone.
Another factor is the typical location and movement of the Intertropical Convergence Zone (ITCZ), a band of low pressure near the equator where winds converge. The ITCZ often remains too close to the equator in the South Atlantic, usually only dipping one or two degrees south. This proximity means the Coriolis force, the rotational force imparted by the Earth necessary to initiate the spinning motion of a storm, is too weak to support the development of a fully rotating tropical system. Furthermore, the lack of tropical waves—the “seed” disturbances that travel off the coast of Africa and fuel North Atlantic hurricanes—also limits the opportunities for storm formation.
Documented Tropical Cyclones Affecting the Brazilian Coast
Despite the generally hostile environment, a few remarkable exceptions have occurred, proving the South Atlantic is not entirely inactive. The most famous and impactful event was Cyclone Catarina in March 2004, the only recorded hurricane-strength tropical cyclone in the South Atlantic basin. Catarina developed from a stationary cold-core low and underwent an unusual tropical transition over the ocean.
The storm rapidly intensified, reaching the equivalent of a Category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale with sustained winds of about 100 miles per hour (160 km/h) before making landfall. Catarina struck the southern coast of Brazil, specifically the states of Santa Catarina and Rio Grande do Sul. It caused an estimated $350 million in damage and resulted in at least three fatalities. Its powerful nature and distinct eye feature forced Brazilian meteorologists to confirm its classification as a hurricane, despite initial debate over the storm’s origin.
While Catarina remains the benchmark for intensity, the Brazilian Navy Hydrographic Center has documented and named other systems that have formed or come close to the Brazilian coast. Examples include Tropical Storm Anita (March 2010), Tropical Storm Iba (March 2019), and Tropical Storm Akará (February 2024). These named storms, along with numerous subtropical cyclones documented since 2011, illustrate that while a strong hurricane is extraordinarily rare, the Brazilian coast is intermittently affected by less intense tropical and subtropical systems.