Cemaden lowers El Niño heat wave forecast for Brazil in 2026By Luís Henrique Costa
3 min read
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Brazil’s National Center for Monitoring and Early Warning of Natural Disasters (Cemaden) has cut its forecast of strong heat waves for the rest of 2026. The agency’s October update keeps alerts for five areas of impact through early 2027, including worsening drought in the North and Northeast and a higher risk of wildfires in the Amazon and the Cerrado savanna.
In late August, the same agency had projected at least six heat waves through December. Its research and development coordinator, José Marengo, said the new calculations point to only a few heat waves. He also cautioned that the season is still in transition: “Of course we are still in spring, summer has not even started, and that can bring changes.”
Drought in the North, rain in the South
Even with the lower peaks of extreme heat, the scientific review finds that El Niño, a warming of surface waters in the equatorial Pacific Ocean, is already changing rainfall across Brazil. In the Amazon and the Northeast, the lack of rain is hampering navigation and water intake and putting more pressure on reservoirs. Dry vegetation, combined with high temperatures, raises the danger of fires in the Amazon forest and the Cerrado.
In the South, persistent rain above the historical average is raising river levels and the risk of floods and waterlogging. Farming faces losses from both water deficit in the Center-North and excess water in the South.
See also: Polar vortex changes and super El Niño cloud US winter forecasts
WMO warns El Niño could reach record strength in 40 years
On October 21, the World Meteorological Organization (WMO), a United Nations agency based in Geneva, warned that the current El Niño could reach unprecedented intensity in four decades. The peak is expected at the end of 2026, with effects running until February 2027. The alert follows research centers’ monitoring of ocean warming and its humanitarian and environmental effects, tracked by WMO Secretary-General Celeste Saulo and UN Under-Secretary-General for Humanitarian Affairs Tom Fletcher.
On October 19, the International Research Institute for Climate and Society (IRI), at Columbia University, reported in a bulletin that warming had already reached +3.3 °C in October in the Niño 3.4 region of the equatorial Pacific. Projections for the peak temperature anomaly vary by the method each scientific institution uses, but the figures compiled by national and international agencies show the scale of the event:
Check out: Met Office seasonal forecast excludes autumn polar vortex freeze despite record El Niño
- Very strong intensity: 95% probability for October to December 2026, according to Bulletin No. 4 of the El Niño Panel (Inmet, Inpe and Cemaden).
- Food security: 50 million people worldwide may face worse hunger because of climate extremes, according to the UN.
- Global mortality: 451,000 additional deaths linked to extreme heat worldwide between 2026 and February 2027, according to a University of Chicago study.
- Sea level: rise of up to 40 centimeters in parts of the equatorial Pacific and a drop in green phytoplankton, making the water bluer, according to October 2026 data from NASA’s PACE satellite.
Why the heat wave forecast changed and how drought is spreading
The earlier Cemaden projection of six heat waves for the second half of 2026 was based on atmospheric patterns recorded during the strong El Niño events of 2015–2016 and 2023–2024. The current episode was officially confirmed in June 2026 by the El Niño Panel, a technical group formed by the Instituto Nacional de Meteorologia (Inmet), the Instituto Nacional de Pesquisas Espaciais (Inpe), the Agência Nacional de Águas e Saneamento Básico (ANA), Cemaden, the Serviço Geológico do Brasil (SGB), the Secretaria Nacional de Proteção e Defesa Civil (Sedec) and the Centro Gestor e Operacional do Sistema de Proteção da Amazônia (Censipam).
Partial Cemaden data for September 2026, released by Inmet, show that the number of Brazilian municipalities in extreme drought rose from 4 to 24 in one month. Cities in severe drought went from 153 to 197, and the condition hits 16% of the Northeast territory hard.
