The tropics are shaped right now by a fading La Niña, record-breaking forest loss driven by fire, warming oceans, and the seasonal rhythms that dictate rainfall for billions of people. Here’s a breakdown of the major forces at play across the tropical belt in 2025.
La Niña Is Fading Into Neutral
The single biggest driver of tropical weather patterns, the El Niño-Southern Oscillation (ENSO) cycle, is currently in a La Niña phase. Sea surface temperatures in the east-central equatorial Pacific were running about 0.9°C below average as of January 2026, enough to keep the La Niña Advisory active at NOAA’s Climate Prediction Center.
That’s expected to change soon. Forecasters put the odds of a transition to ENSO-neutral conditions at 60% between February and April 2026, with neutral conditions likely persisting through the Northern Hemisphere summer. Looking further out, there’s a 50 to 60% chance El Niño forms by late summer, though predictions made this early in the year carry significant uncertainty.
Why does this matter? La Niña tends to suppress rainfall in parts of equatorial East Africa and the southern United States while boosting it across Southeast Asia, northern Australia, and the Amazon. As that influence weakens, regions that have been unusually wet or dry over the past several months will start shifting back toward their baseline climate. An El Niño later in the year would flip the script again, bringing drought risk to Southeast Asia and Australia and heavier rains to the eastern Pacific coast of South America.
Tropical Forest Loss Hit a Post-2016 High
The Amazon biome lost more tree cover in 2024 than in any year since the record high in 2016, with total loss jumping 110% compared to 2023. The overwhelming cause was fire: roughly 60% of the Amazon’s 2024 tree cover loss was fire-driven, according to data compiled by the World Resources Institute. That makes 2024 the worst fire year for the Amazon in nearly a decade.
The fires weren’t random. Severe drought across large parts of the Amazon basin, partly linked to the El Niño that preceded the current La Niña, dried out vegetation that would normally be too wet to burn. Once those conditions align, fires set for land clearing or agriculture can escape and sweep through standing forest. The result was a year in which fire did more damage to the world’s largest tropical rainforest than deliberate deforestation in many prior years.
This matters well beyond the Amazon itself. Tropical forests absorb enormous amounts of carbon dioxide, and when they burn, that stored carbon is released back into the atmosphere. Large-scale forest loss also disrupts regional rainfall cycles. The Amazon generates a significant share of its own precipitation through moisture recycled by trees, so each major fire season erodes the forest’s ability to sustain itself in the future.
Tropical Oceans Are Running Hot
Even with La Niña cooling the central Pacific, tropical ocean temperatures broadly remain above historical averages. NASA satellite data from mid-2025 showed sea surface temperature anomalies reaching about 3°C above normal in the hottest patches, with widespread warming visible across multiple ocean basins.
The western Indian Ocean has been a particular hotspot. Marine heatwaves, defined as periods when ocean temperatures exceed the 90th percentile of historical readings, have been increasing in the Indian Ocean at a rate of 1.2 to 1.5 additional events per decade in the western region. The north Bay of Bengal follows at 0.4 to 0.5 additional events per decade. These aren’t abstract statistics: marine heatwaves bleach coral, collapse fisheries, and intensify the moisture feeding into monsoon systems.
Warmer ocean surfaces also load the atmosphere with more water vapor, which acts as fuel for tropical storms. While the 2025 Atlantic hurricane season has wound down with no active disturbances in the final outlook, the underlying ocean heat that feeds cyclone development hasn’t gone anywhere. Forecasters will be watching closely to see whether a possible El Niño later in 2026 suppresses Atlantic hurricane activity (as it typically does) or whether background ocean warmth overwhelms that effect.
How Tropical Rainfall Seasons Work
The engine behind wet and dry seasons in the tropics is the Intertropical Convergence Zone, or ITCZ, a belt of clouds and thunderstorms that wraps the globe near the equator. It forms where trade winds from both hemispheres collide and force air upward, generating intense convective rainfall. An estimated 40% of all tropical rain falls at rates exceeding one inch per hour.
The ITCZ follows the sun. It shifts northward during the Northern Hemisphere summer and southward during winter. Near the equator, this creates two wet seasons per year: one around March and another around September, when the sun crosses directly overhead. Two corresponding dry seasons fall near December and July. Move further from the equator and those two wet periods merge into a single monsoon season, typically May through July in the Northern Hemisphere and November through February in the Southern Hemisphere.
Right now, with the Northern Hemisphere in winter, the ITCZ sits south of the equator, delivering peak wet-season rainfall to places like northern Australia, Indonesia, central Africa south of the equator, and Brazil. Northern tropical regions, including the Caribbean, Central America, and West Africa, are in their dry season. This pattern will reverse over the coming months as the sun migrates north, bringing the onset of monsoon rains to South and Southeast Asia by May or June.
What It All Adds Up To
The tropics in early 2026 sit at a transition point. La Niña’s cooling grip on the Pacific is loosening, which will reshuffle rainfall patterns across three continents. Ocean temperatures remain stubbornly elevated, sustaining marine heatwaves and priming the atmosphere for intense storms. And the Amazon is still reeling from a historically destructive fire season that underscored how drought, heat, and land use interact to threaten irreplaceable ecosystems. As the ITCZ begins its annual northward march and ENSO trends toward neutral or possibly El Niño conditions, the second half of 2026 could look dramatically different from the first.