The U.S. Oceanic and Atmospheric Administration (NOAA) has raised the probability of the El Niño phenomenon reaching a very strong intensity for the period between October and December 2026 to 95%. This estimate was presented in an update released this Thursday, the 13th.
In its previous report, dated July 9, the agency had calculated this chance at 81% for the same time frame.
Additionally, for the period between November 2026 and January 2027, which covers the end of spring and the beginning of summer in the Southern Hemisphere, NOAA currently projects a 90% probability of a very intense El Niño.
The agency also points out that there is a 69% chance that this episode will be among the largest El Niños recorded since 1950, considering current projections regarding Pacific Ocean temperatures.
This adjustment in forecasts occurs at a time when the warming of the Equatorial Pacific waters is intensifying. A value of 1.8 °C is already considered by Climatempo as compatible with a strong El Niño, although NOAA was classifying the phenomenon as strengthening, without officially designating it as strong in the previous monthly bulletin.
The final determination of El Niño's intensity will depend on how the Equatorial Pacific continues to warm in the coming months and, crucially, how the atmosphere reacts to this warming. For the phenomenon to consolidate, it is not enough just for the ocean temperature to rise; it is imperative that the integrated system between the ocean and atmosphere begins to operate persistently and coupledly.
El Niño is defined by the unusual warming of the waters of the Equatorial Pacific Ocean, technically occurring when the temperature of these waters exceeds the average by 0.5 °C or more. It is part of the natural cycle of the climate system known as El Niño-Southern Oscillation (ENSO), which alternates between warm phases (associated with El Niño), cold phases (related to La Niña), and neutral periods.
Warming in the Pacific alters atmospheric circulation, which can modify rainfall and temperature patterns in various parts of the globe. This event typically occurs every two to seven years and has an average duration of about 12 months, also contributing to the increase in global average temperature during its peak intensity.
La Niña
La Niña represents the opposite phase of this cycle, characterized by the cooling of the same Pacific waters and generating climatic impacts that, in many regions, occur in the opposite direction.
In Brazil, the effects of El Niño vary depending on the region and the season. Given that the greatest intensity of the current episode is expected between November and January, the impacts during spring and summer deserve special attention.
Historically, the phenomenon tends to cause different conditions: in the Southeast and Central-West, the effects are less homogeneous and may involve higher temperatures along with irregular rainfall.
It is important to note that the impacts of El Niño are not solely determined by ocean temperature; the atmosphere's response to the Pacific warming is equally essential in determining the intensity and distribution of these effects. Since 2006, the planet has been experiencing a series of El Niño episodes in a context of temperatures already above historical records.
Even events classified as weak or moderate can raise the risk of extreme weather events in a scenario of global warming, encompassing droughts, floods, and heatwaves. Among the main episodes of the last two decades are those that demonstrate the growing trend.
Current expectations point to a strengthening of the 2026 episode in the coming months, with a high probability of reaching very strong intensity, although its evolution depends on the maintenance of Pacific warming and atmospheric behavior. Experts emphasize that global warming remains the primary long-term factor behind climate changes, causing El Niño episodes to drive even higher temperatures and increase the risk of global extremes.
