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The Equatorial Pacific reached a temperature anomaly of +0.5ºC, the minimum value for characterizing El Niño, for the first time this year, according to a NOAA bulletin released by the portal Metsul this Monday (20), and the trend is for even greater warming in the coming weeks, with a risk of intense rains in the South and drought in the Northeast of Brazil.
The El Niño has shown concrete signs of life in the Pacific Ocean again. According to the weekly bulletin from the National Oceanic and Atmospheric Administration (NOAA), the sea surface temperature anomaly in the Niño 3.4 region, the zone officially used to classify the state of the phenomenon, reached +0.5ºC. This value represents the floor of the range considered the warm phase of the ocean and marks the first time in 2026 that the Central-Eastern Equatorial Pacific has reached the minimum level associated with El Niño.
The last time this region of the Pacific recorded an anomaly equal to or greater than +0.5ºC was in the week of May 1, 2024, a period when Rio Grande do Sul faced the disaster of flooding caused by accumulated ocean warming in the previous months. This data raises an important weather alert for Brazil, as the phenomenon is directly linked to extreme climate patterns in different regions of the country.
What is happening in the depths of the Pacific and why El Niño may strengthen
The warming recorded at the surface of the Equatorial Pacific did not come from nowhere. A Kelvin Wave, an oceanic mechanism that transports warm water masses from the depths to the surface, is pushing warmer waters from West to East along the equatorial band. This process explains why the anomaly jumped to the threshold of El Niño in recent weeks, even after a prolonged period of oceanic neutrality.
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The critical point is that there is still a large volume of warm water below the surface of the Pacific. This means that the trend in the coming weeks is for additional warming, which could raise the anomaly to more significant values and bring the ocean closer to a full El Niño configuration. MetSul Meteorologia emphasizes, however, that a single week with an anomaly of +0.5ºC is not sufficient to officially declare the onset of the phenomenon. Several consecutive weeks above this threshold are needed for El Niño to be formally recognized.
When El Niño can be officially declared in 2026
Experts expect the phenomenon to be fully established between late autumn and early winter, possibly by mid-May or, at the latest, in June. For this to happen, it is not enough for the ocean to warm at the surface. There must be what is called coupling between the ocean and the atmosphere, when the trade winds weaken in the equatorial region and begin to reinforce the warming of the water.
As long as this coupling is not completed, the Pacific remains in a transition zone between neutrality and El Niño. The difference between being on the brink and having the phenomenon fully active is enormous in terms of climate impact. A configured El Niño alters rainfall and temperature patterns on a global scale, while an isolated anomaly may dissipate without generating significant consequences. Therefore, the coming weeks will be decisive in confirming or not the establishment of the phenomenon.
How El Niño affects the climate in Brazil and what to expect this time
The effects of El Niño on Brazilian territory follow a well-documented pattern in meteorology. In the South of the country, the phenomenon increases the risk of excessive rains and floods, exactly the scenario that devastated Rio Grande do Sul in May 2024 during the previous episode. In the Northeast, the dynamics are reversed: El Niño intensifies drought, reducing rainfall in a region that already suffers from chronic water deficits in various locations.
In the economic field, the phenomenon also produces relevant consequences. Historically, the best agricultural harvests in Southern Brazil occur during El Niño years, although excessive rain can cause localized losses in certain crops. This dynamic directly affects the supply and prices of food, with repercussions that extend throughout the production chain. For the Northeast, the risk of prolonged drought may compromise family farming and pressure water supply in communities that depend on already weakened reservoirs.
The largest El Niño episodes ever recorded and how they compare to the current scenario
To gauge what may be coming, it’s worth looking at previous events. In the El Niño of 2023-2024, the maximum anomaly in the Central-Eastern Equatorial Pacific reached +2.1ºC in the week of November 22, 2023. The episode of 2015-2016 was even more intense, peaking at +3.0ºC in November 2015. The event of 1997-1998 recorded a maximum anomaly of +2.3ºC, and that of 1982-1983 reached +2.6ºC, both considered among the most severe of the last century.
The current scenario, with an anomaly of +0.5ºC, is far from these peaks. However, the fact that there is a large volume of warm water below the surface indicates that the potential for intensification exists. How much the phenomenon will strengthen will depend on the evolution of the Kelvin Waves, the behavior of the trade winds, and the atmospheric response to ocean warming in the coming weeks. Each additional fraction of a degree in the Pacific anomaly could mean significant changes in Brazil’s rainfall regime between winter and spring, increasing both the risk of flooding in the South and prolonged drought in the semi-arid region.
Are you concerned about the effects of a possible El Niño on your region’s climate? Share in the comments how the phenomenon has affected your city in previous years; your experience can help other readers prepare for what may lie ahead.
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