The Amazon Cooperation Treaty Organization (OTCA) has named El Nino the climate factor most worth watching in 2026. The latest bulletin from the U.S. NOAA puts the odds of formation in May-July at 61%. Across the drier northeastern Amazon, northern Brazil, Colombia and Venezuela, the concern is spreading wildfire and sharply falling river levels.
[Update, July 20, 2026]
El Nino has since actually formed. NOAA/CPC issued an El Nino Advisory on June 11, and the Nino 3.4 index climbed to +1.7°C by mid-June. Forecasts now widely favor a high probability of reaching "very strong" levels (+2.0°C or more) into the fall (September-November). The article's original read at the time of writing β that a weak-to-moderate event was most likely, with only about a 20% chance of high intensity β needs to be revised upward. Read what follows against a harsher premise: a stronger El Nino layered on top of already dried-out land.
What 61% Means
El Nino is a warming of sea-surface temperatures in the tropical Pacific that brings broad drought to South America. At the time of writing, OTCA read it as a transitional scenario β most likely a weak-to-moderate event lasting through year-end (all figures reflect forecasts from April-May 2026). The odds of a high-intensity event were put at about 20% in CIIFEN's April bulletin. The numbers deserve a calm reading (for how the event actually unfolded, see the update at the top).
That said, weak does not mean no impact. Temperature anomalies in the tropical Atlantic can shift Amazon rainfall and apply drying pressure that exceeds the Pacific-side effect. The state of the soil and vegetation amplifies it further.
First, the Rivers Fall
When rain declines, river levels drop first. Much of life along the basin depends on river transport, and falling water feeds straight into daily life. In the great drought of 2023, record low levels persisted on Amazon tributaries; settlements were cut off, and food and medicine grew hard to deliver. The warning is that the same could come in the second half of 2026.
Wildfire risk stacks on top. When dry vegetation meets fires set to clear land for farming, flames spread easily. The Lula government has championed Amazon protection heading into COP30 (held in Belem in 2025), yet, as a $75 million investment in the BR-319 highway shows, the tug-of-war between development and protection continues.
Even Drought-Tolerant Trees Begin to Fail
What makes El Nino difficult is that it does not act alone; it combines with long-term climate change. A study published in Nature in May 2026 showed that deforestation-induced drying lowers the Amazon's climate threshold. Even tree species that should resist drought are beginning to fail when rising heat and falling rainfall coincide. OTCA is calling on its eight member states to build early-warning systems and strengthen cross-border firefighting. It starts with reading the monitored numbers accurately.
Even when the size estimates keep shifting, on land that has dried out completely a small spark can turn into a large fire.
π Go deeper Β· Related books
Want to explore this topic further? Find related books on Amazon.
Find related books (Amazon) βThis article contains Amazon affiliate links. See our Privacy Policy for details.
References
- El Nino in the Amazon and its climate impacts 2026 β OTCA β otca.org
- Fire Frontiers: Regional cooperation to protect the Amazon, El Nino 2026 β OTCA β otca.org
- Deforestation-induced drying lowers Amazon climate threshold β Nature (2026) β nature.com
- Cropped 3 June 2026: Highway through the Amazon | El Nino impact β Carbon Brief β carbonbrief.org
β» This article is the authorβs commentary based on public information. Please confirm the latest figures, dates and procedures with governments and primary sources. Quotations are kept minimal and sources are cited.