Brazilian meteorological services forecast a heat wave and increased thunderstorm risks for southern states starting July 16, 2026 [4].
These extreme weather shifts pose significant risks to public health and infrastructure, particularly in regions already vulnerable to sudden atmospheric instability.
The Instituto Nacional de Meteorologia (Inmet) said that a heat wave will affect four states: Mato Grosso do Sul, Santa Catarina, Paraná, and Rio Grande do Sul [2]. This phenomenon, known as a *veranico*, involves a hot and dry air mass that can push temperatures up to five degrees Celsius above the seasonal average [1].
While the heat persists, meteorologists are monitoring a high risk of thunderstorms and heavy rain in Rio Grande do Sul. Some reports indicate this risk began on Thursday, July 16 [4], while others emphasize the danger for Friday, July 17 [3].
Experts said the volatility is due to a combination of the *veranico* and atmospheric conditions driven by El Niño [2]. This combination creates instability that favors the development of severe storms. Other reports link the thunderstorm risk to an approaching cold front, though the influence of El Niño remains a primary factor in the regional forecast [2].
Beyond the south, heat is also expected to impact São Paulo, Minas Gerais, and Rio de Janeiro [3]. Inmet has issued alerts regarding the health risks associated with these unusually high temperatures during the winter months.
The period of highest concern spans from Friday, July 17, through the following weekend [3]. Residents in the affected states are advised to monitor local alerts as the interaction between the hot air mass and the El Niño-driven instability continues to evolve.
“Temperatures up to 5°C above the average”
The occurrence of a *veranico* during the winter months, amplified by El Niño, demonstrates the increasing volatility of South American weather patterns. The rapid transition from extreme heat to severe thunderstorms creates a dual threat of heat-related health crises and flash flooding, complicating emergency management for local governments in Southern Brazil.
