Inmet: what to expect from La Niña in the Brazilian climate in 2025?

The planet is already under the effects of the La Niña climate phenomenon, as announced by NOAA (National Oceanic and Atmospheric Administration) in January of this year. But how does this phenomenon impact Brazil?

Meteorologist Danielle Ferreira from the National Institute of Meteorology (Inmet) explains that, in La Niña years, there is a reduction in rainfall in the Southern Region of Brazil, both in quantity and frequency, with the possibility of some long periods without rainfall.

However, it is not only in the South of Brazil that La Niña has a strong impact. All this movement that characterizes the phenomenon originates in the Equatorial Pacific Ocean and reverberates, in different ways, in several other regions.

In the northern strip of the North and Northeast regions of Brazil, the opposite occurs: excess rain, which is currently happening in a large part of these areas, with constant orange warnings of danger for heavy rain.

“Cold fronts pass more quickly over the eastern part of the South Region and end up bringing more rain to the Southeast Region, and can even reach part of the Northeast coast. This typical behavior does not always occur, as it is also necessary to consider other factors such as the temperature of the Atlantic Ocean (Tropical and Southeast of South America), which can also mitigate or intensify the impacts of the phenomenon”, says the meteorologist.

The warming of the Tropical Atlantic, for example, favors the occurrence of rain in the North of Brazil, due to the displacement of the Intertropical Convergence Zone (ITCZ) further south from its climatological position.

Importance of the ocean

Both La Niña and El Niño form in the Equatorial Pacific Ocean, which reinforces the theory that the oceans exert a great influence on the climate in different parts of the planet.

Danielle explains the difference between these two climate phenomena: El Niño is the anomalous warming of the waters of the Equatorial Pacific, while La Niña is characterized by the anomalous cooling of the waters of these waters. “That is why it is important to monitor their conditions,” she emphasizes.

Thus, in the so-called Niño 3.4 Region (area between 170°W and 120°W), sea surface temperatures (SST) have been observed with a value of 0,5°C below average since October/2024 and in December/2024, it reached the level of 1,0°C below average, indicating the presence of colder waters than normal.

The persistence of these anomalies (difference between the observed value and the average) for three consecutive months characterizes the La Niña phenomenon. The phenomenon is expected to persist during the February-March-April quarter of 2025, with a 59% probability (Figure 1).

For the coming months, above-average temperatures are expected in much of Brazil and more concentrated rainfall in the North, Central-West and northern and western areas of the Northeast Region, in the first quarter of 2025.