La Niña is here: What does it mean for Latin America and the Caribbean?

La Niña, a phenomenon characterized by the cooling of the Pacific Ocean and which has been anticipated since September 2024, is already here. At the beginning of January of this year, international meteorological agencies announced that a weak Niña is expected to persist until April, with a 59% probability, and to evolve into neutral conditions in May, with a 60% probability. La Niña is a phenomenon of climatic variability that alternates with El Niño and neutral conditions over periods that can last months or years. While La Niña usually lasts longer, El Niño, which predominated between mid-2023 and early 2024, occurs in shorter periods and is characterized by warmer ocean temperatures.

EL PAÍS spoke with meteorologists to understand how this phenomenon could impact Latin America and the Caribbean.

What to expect?

Barbara Tapia Cortés of the World Meteorological Organization (WMO) explains that La Niña typically brings wetter conditions to Central America and northern South America, while central and southern South America tend to experience drier conditions. “If La Niña persists, we are likely to see a shortage of rainfall in central and southern South America, while northern South America and Central America could experience an increase in rainfall.”

Meanwhile, Cuban hurricane specialist José Rubiera also provides some clues: “Although temperatures are moderated a bit, there may be droughts in southern California, in some areas of Central America, Ecuador, Peru, and central Chile,” he says. At the same time, rain will be more predominant in southeastern and central Mexico, Colombia, the Caribbean, and the Pacific zone of Central America.

What does a weak Niña mean?

Both La Niña and El Niño are determined by a key criterion: whether the temperature of the central and eastern equatorial Pacific Ocean rises or falls by 0.5°C compared to the average. Depending on how far it deviates from that equilibrium, it is considered either a strong or weak phenomenon. However, as Tapia points out, “this intensity does not go hand in hand with what a person perceives, or how it affects a community.” Just because a Niña is weak does not mean that its impacts are also weak, and that is why countries must prepare.

Can the cooling effect of La Niña mitigate the heat of recent years?

Broadly speaking, the answer is no. What is happening in the equatorial Pacific Ocean is too small to have an impact on global temperatures, which are generally rising due to climate change. “It may moderate the temperature slightly, but it will not prevent 2025 from continuing to be one of the hottest years in history,” says Rubiera: 2024 was the first year to reach 1.5 degrees Celsius above pre-industrial levels.

The sea, Tapia adds, is like a huge tub, which only warms up or cools down after a long time. And La Niña, along with its cooling, is not strong enough and doesn’t last long enough to change the current trend.

La Niña and hurricane season: how does the mix work?

As Rubiera says, “in this case, two plus two does not equal four.” According to forecasts, there is a probability that by the time hurricane season begins, both in the Pacific (May) and the Atlantic (June), La Niña will be easing or conditions will already be neutral. Despite this, he does not rule out that “the hurricane season will be slightly more active.”

Why? First, because despite the temporary cooling of the Pacific Ocean, this does not mean that the sea is not still warm in itself — something that has driven climate change — which serves as an engine for hurricanes. And, second, because the trend is that, during La Niña or even with neutral conditions, it is increasingly common for more active hurricane seasons to occur in the Atlantic. This happens, according to experts, because for a hurricane to fully form, it must build a kind of structure of vertical currents. With El Niño, which in turn brings strong winds, it is more difficult for that structure to maintain itself.

“We can imagine a pyramid of cards. Without much wind, like during La Niña or neutral conditions, the cards stay there. But if you blow on them [similar to what El Niño does] they will collapse,” Tapia says. That is why seasons are generally more active during La Niña.

However, Rubiera adds, there are other factors, including climate change, that are altering the situation. “Last year, with El Niño, the season was very active, in principle, because the water in the Atlantic Ocean was very, very warm. That overcame any effect that El Niño had with the strong upper currents, which are the ones that inhibit cyclone formation.”

In light of this, Rubiera and Tapia leave two clear messages. The first is that we are beginning to see how the dynamics of climate variability work in a context of climate change in which, in addition, extreme events will become more frequent. The second is the need to prepare and be attentive to national meteorological services. “It has been proven that extreme events are increasingly harmful to the population, affecting property and, when there are no efficient warning systems, they leave people injured or dead,” warns Tapia. The phenomenon of La Niña has been forewarned and, all things considered, is providing time to prepare, whether for droughts, floods, or active hurricane seasons in the region.

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