Floods in Asia and early snowfall across the US are signaling the return of La Nina, a phenomenon of cold sea water in the Pacific Ocean, which could disrupt economies and trigger disasters globally.
According to Aon - a reinsurance brokerage and data analysis company, in recent La Nina years, total global losses have ranged from 258 billion to 329 billion USD.
Although the level of damage varies from year to year, the general trend is very clear: Extreme weather is pushing up damage.
La Nina could aggravate both droughts and heavy rains, prompting stronger storms in the tropical Pacific and intensifying Atlantic hurricanes.
Not all extreme weather phenomena can be directly attributed to La Nina, but scientists say that the fingerprints of La Nina are very familiar.
La Nina is like a traffic police in rush hour, regulating traffic or weather systems in certain directions, said Ms. Michelle LHeureux, a forecaster at the US Climate Prediction Center.
She also compared La Nina to the conductor of a weather symphony. Although La Nina often follows a common pattern, each period is different and other factors can affect the final outcome.
The current La Nina is the 5th in the past 6 years.
Even a weak La Nina can leave a strong impression. According to the storm research team analyzed in the World Weather Attribution project, La Nina is likely to be part of the "formula" leading to a series of devastating storms and floods that killed more than 1,600 people and caused at least 20 billion USD in damage in South Asia and Southeast Asia.
According to data compiled by Bloomberg, floods in Vietnam and Thailand in November and December 2025 killed at least 500 people, causing damage and losses of more than 16 billion USD.
The role of La Nina in these natural disasters cannot be confirmed, but the development model is consistent with the behavior of this phenomenon in the past, said Ms. L'Heureux.
La Ninas contribution to higher-than-normal rainfall in Southeast Asia is killing lives and damaging infrastructure, said Bill Hare, CEO of Climate Analytics.
The current La Nina is likely to peak or will peak in the next few weeks. After that, conditions in the equatorial Pacific are expected to return to neutral. However, even if the Pacific returns to a more normal state, it does not mean that changes in global weather will end. La Nina conditions could continue for months.
