The summer of 2024-2025, which ended at 6:02 AM on Thursday (March 20), was the sixth hottest in Brazil since 1961, with temperatures 0.34°C above the historical average for the 1991-2020 period.
Temperatures remained above average across much of Brazil. The highest maximum temperatures were recorded mainly in Rio Grande do Sul, where three heat waves occurred: from January 17 to 23, February 2 to 12, and March 1 to 8, 2025.
Even under the influence of La Niña, which generally lowers global average temperatures, this summer ranked among the ten hottest on record. Summer temperatures in Brazil have been above average since the 1990s.
The summers of 2023-2024, 2015-2016, 1997-1998, and 2009-2010 were influenced by El Niño, a phenomenon characterized by above-average warming of the equatorial Pacific Ocean, which intensifies temperature increases in various regions of the planet.
The fact is that, for Brazil, the last decade has been hotter than the previous one. The World Meteorological Organization (WMO) has warned about the increase in greenhouse gas emissions and global warming.
A rainy summer
Alongside high temperatures, the summer of 2024-2025 was also marked by heavy rainfall, especially in the northern region, Maranhão, and northern Piauí, where precipitation exceeded 700 mm, with many locations surpassing historical averages.
The frequent storms in northern Brazil were primarily driven by the Intertropical Convergence Zone (ITCZ), a meteorological system formed by the convergence of trade winds from the northeast (originating in the Northern Hemisphere) and southeast (from the Southern Hemisphere).
Rainfall exceeded 500 mm in the central-northern region, except for Roraima, central-eastern Northeast, southern Mato Grosso do Sul, western São Paulo, northern Minas Gerais, Espírito Santo, Rio de Janeiro, and central and western parts of the South region, where lower precipitation levels were observed.
In the Central-West and Southeast regions, rainfall was predominantly below average, with amounts exceeding 600 mm in northern Mato Grosso and isolated areas of Goiás and São Paulo. In other areas, rainfall totals ranged between 300 and 500 mm. This summer saw three episodes of the South Atlantic Convergence Zone (SACZ): the first from December 27 to 31, 2024, the second from January 6 to 15, 2025, and the last from January 31 to February 5, 2025.
In the South region, the passage of frontal systems and unstable weather conditions led to rainfall exceeding 500 mm in eastern Paraná and Santa Catarina. In other areas, rainfall was below average, particularly in western Rio Grande do Sul, where summer precipitation remained below 250 mm, despite the historical average for this period ranging between 400 and 500 mm.
(Source: INMET)