Cemaden cuts El Niño heat wave forecast for Brazil until end of 2026By Manuela
4 min read
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The National Center for Monitoring and Alerts of Natural Disasters (Cemaden) revised its El Niño forecasts for Brazil and reduced its estimate of strong heat waves through the end of 2026. The diagnosis, updated in October 2026, keeps alerts for five impact fronts in the country until early 2027, including advancing drought in the North and Northeast and a greater risk of wildfires in the Amazon and the Cerrado.
The new assessment changes the scenario the agency had drawn at the end of August 2026, when researchers projected at least six heat waves by December. “New calculations we made show a perspective of few heat waves,” said José Marengo, Cemaden’s general coordinator of research and development. He warned that the change of seasons still needs monitoring: “Of course we are still in spring, summer has not even started, which may bring changes.”
Even with the lower forecast for extreme heat peaks, the scientific survey shows that El Niño, a phenomenon marked by abnormal warming of surface waters in the equatorial Pacific Ocean, is already changing rainfall in several Brazilian regions. In the Amazon and the Northeast, the lack of rain hurts navigation and water capture and increases pressure on reservoirs, while dry vegetation tied to high temperatures raises the danger of fires in the rainforest and the Cerrado. In the South, persistent rain above the historical average raises river levels and the risk of floods, which threatens agribusiness with simultaneous losses from water deficit in the Center-North and excess water in the South.
Read also: Met Office seasonal forecast excludes autumn polar vortex freeze despite record El Niño
WMO warns El Niño could reach an intensity not seen in 40 years
On October 21, 2026, the World Meteorological Organization (WMO), a United Nations agency based in Geneva, warned that the current El Niño may reach an unprecedented intensity in the last four decades, peaking at the end of 2026 and lasting until February 2027. The international alert comes alongside analyses from research centers that track the warming of the ocean and its humanitarian and environmental effects on a global scale. WMO Secretary-General Celeste Saulo and UN Under-Secretary-General for Humanitarian Affairs Tom Fletcher are following the developments.
On October 19, 2026, the International Research Institute for Climate and Society (IRI), at Columbia University, reported that the warming had already reached +3.3°C in October in the Niño 3.4 region of the equatorial Pacific. Projections for the maximum temperature anomaly vary with the method each institution uses, but the figures compiled by national and international agencies show the scale of the event:
- Probability of very strong intensity: 95% for October to December 2026, according to Bulletin No. 4 of the Painel El Niño (Inmet, Inpe and Cemaden).
- Food security: 50 million people worldwide may face worsening hunger due to extreme climate events, 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.
- Ocean change measured by NASA: sea level rise of up to 40 centimeters in parts of the equatorial Pacific and a drop in green phytoplankton, which makes the water bluer, according to October 2026 data from the PACE satellite.
Earlier forecast relied on 2015/16 and 2023/24 events
The earlier Cemaden forecast, which projected six heat waves for the second half of 2026, was based on atmospheric behavior recorded during the strong El Niño episodes of 2015/2016 and 2023/2024. The current episode was officially confirmed in June 2026 by the Painel El Niño, a technical group formed by the National Institute of Meteorology (Inmet), the National Institute for Space Research (Inpe), the National Water and Sanitation Agency (ANA), Cemaden, the Geological Survey of Brazil (SGB), the National Secretariat for Civil Defense and Protection (Sedec) and the Center for Operational Management of the Amazon Protection System (Censipam).
Keep reading: Super El Niño heat waves could cause 451,000 deaths worldwide with Brazil among most vulnerable nations
Partial Cemaden data for September 2026, released by Inmet, show that the number of municipalities in extreme drought rose from 4 to 24 in one month. Cities in severe drought went from 153 to 197, severely affecting 16% of the Northeast’s territory.
