Deadly flooding in Asia and early blizzards across the U.S. are signaling the return of weather-driven La Nina, the cooling of Pacific waters that can disrupt economies around the world and trigger catastrophic disasters.
In recent La Niña years, global losses have increased from $258 billion to $329 billion, according to an insurance broker and data analysis firm. Despite year-to-year swings in loss totals, the overall momentum is unmistakable: extreme weather is increasing losses. The La Niña phenomenon is often associated with droughts in California, Argentina, and Brazil, and the devastating floods that recently swept through Southeast Asia. This type of catastrophe has become a major factor in setting terms for insurance companies, farmers and energy suppliers.
La Niña can intensify both drought and rainfall, promote more active storms in the tropical Pacific and strengthen Atlantic hurricanes. During past episodes, this pattern may have helped fuel fires in Los Angeles in January and Hurricane Helene, which killed more than 250 people in South America in 2024. Not every extreme event can be directly tied to La Niña, but scientists say the fingerprints are familiar.
“La Niña is like the traffic police in the middle of rush hour, helping the flow of cars or weather systems in certain preferred directions,” said Michelle L. Heureux, a forecaster at the U.S. Climate Prediction Center. He has also likened it to “the conductor of a seasonal symphony” or an American football quarterback calling plays. Although La Niña follows a general pattern, El Heureux points out that each event is different and other factors can affect the final results. El Heureux said that La Niña does not usually have a major impact on the weather in Europe.
The current La Niña is the fifth in six years, part of a broader trend toward more La Niñas than El Niños (warming of Pacific Ocean waters) over the past quarter century. Scientists are still studying this change. Some suggest climate change is affecting the cycle, while others attribute it to natural variability, El Heureux said.
The ripple effects can reach even deeper into global markets. According to research published in the journal “Environmental Development,” La Niña is often associated with lower yields of corn, rice and wheat. Energy demand generally increases fuel consumption and stress efficiency when cooler temperatures settle over the northern parts of the US, China and Japan. These results can raise the prices of some commodities while simultaneously squeezing others.
Tool of Asia
Even a weak La Nina can leave a heavy footprint. The weather pattern was part of the recipe for a series of tropical cyclones and devastating floods that killed more than 1,600 people and caused at least $20 billion in damage in South and Southeast Asia, according to a team of researchers who investigated the storm as part of a global climate linkage analysis.
Floods in Vietnam and Thailand in November and December killed at least 500 people and caused more than $16 billion in damage and losses, according to data compiled by Bloomberg. Although La Niña’s role in these disasters is not certain, its pattern is consistent with its past behavior.
“La Niña’s contribution to unusual rainfall in Southeast Asia is costing lives and damaging infrastructure,” said Bill Hare, chief executive officer of Climate Analytics.
China faces its own risks. Lower-than-average temperatures could threaten winter wheat production, said Luz Rook, market intelligence coordinator at HedgePoint Global Markets. This risk, as well as impacts elsewhere, will be mitigated by the weakening of the current La Niña.
Kang Wei-Chiang, an agricultural broker at Stonex Group Inc. in Singapore, said palm oil producers in Southeast Asia could see oil extraction rates rise as heavy rains disrupt harvests and disrupt transportation. At the same time, crops can benefit from increased moisture in about five to 12 months by promoting tree recovery and clump formation.
We Outlook
In North America, La Niña typically produces cold and snowy conditions in western Canada, the Pacific Northwest, the northern Rockies and the Great Lakes region, said Clark University geography professor Abby Frazier. According to the National Weather Service, Chicago had its record snow day for November this year, and large areas of central and northern New England saw more than seven inches, with some spots approaching a foot.
Matt Rogers, president of Commodity Weather Group, said November was cooler than last year but warmer than the 10-year average, measured by the heating degree day measure, a way to track temperature-driven energy demand. It was colder than normal in the densely populated American Northeast.
“It’s helping, it’s not the whole reason, but it’s helping,” he said, “it’s helping,” he said, “it’s helping to help,” he said, adding to the cold, snow-covered conditions in North America from La Niña. “
Clark University’s Frazier said La Niña’s influence in the US Southwest is generally skewed toward drought, a pattern that could spread to Southern California. However, there are instances where other weather patterns, such as extreme oceanic heat waves in the Pacific Ocean, can increase expectations, according to Jennifer Francis, a climate scientist at the Woodville Climate Research Center.
“A good example of this was the winter of 2022-23, the third in a row of La Niña conditions,” Francis said. “That winter was California’s worst in two decades.”
Global threats
Brazil, the world’s top soybean exporter, is looking for signs La Niña could reduce rainfall in parts of its southern growing regions. Forecasts indicate irregular rain in the central and southern parts of the country, said Marco Antonio dos Santos, a meteorologist at the Department of Meteorology, adding that concerns were downplayed because there was no sign of drought periods lasting more than 20 days.
In the country’s southern state of Rio Grande do Sul, soy planting is slightly delayed but progressing, said agronomist Paulo Ruggeri. “The stress is that we could have a drier December, but it will all depend on the severity of the drought,” he added.
According to commercial forecaster Agnitia, conditions in the Maritime Subcontinent are expected to dry in December while rains continue in Vietnam.
Abnormal rainfall can help some fields and hurt others, but the risk comes after rains come out or skip prime growth, “turning professional activity into a lottery game with bad odds,” said Andreas Wallgren, Ignatia’s chief science officer.
Climate layer
According to Hare of Climate Analytics, although La Nina is a naturally occurring cycle, its effects are “modified and amplified by global warming”.
“While they differ from the long-term warming trend due to human activity—especially the continued burning of fossil fuels, which is driving catastrophic changes in temperature and precipitation extremes around the world—they are modulating and to some extent amplifying global warming trends,” Herr said.
As for the current La Niña, it is likely to be building up now, or will be in the next few weeks, and then conditions in the equatorial Pacific Ocean are forecast to be neutral, he said. Even if the Pacific returns to a more normal state, that doesn’t mean global climate change will end. La Niña conditions can last for months.
Copyright 2025 Bloomberg.
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