(Bloomberg) — Deadly flooding in Asia and early snowstorms across the US are signaling the return of a weather-roiling La Niña, a cooling of Pacific waters that can disrupt economies and trigger disasters worldwide.In recent La Niña years, global losses have ranged from $258 billion to $329 billion, according to Aon, a reinsurance broker and data analysis firm. Despite year-to-year swings in damage totals, the overall trajectory is unmistakable: Extreme weather is pushing losses higher. The La Niña phenomenon is often linked with droughts in California, Argentina and Brazil, and the destructive flooding that recently swept Southeast Asia. These types of catastrophes have become a larger factor in setting terms for insurers, farmers and energy providers.La Niña can intensify both droughts and downpours, fuel more active storms across the tropical Pacific and strengthen Atlantic hurricanes. During past episodes, the pattern may have helped drive the Los Angeles fires in January and Hurricane Helene, which killed more than 250 people across the southern US in 2024. Not every extreme event can be tied directly to La Niña, but scientists say the fingerprints are familiar.“La Niña is like a traffic cop in the middle of rush hour, aiding the flow of cars or weather systems in certain preferred directions,” said Michelle L’Heureux, a forecaster with the US Climate Prediction Center. She has also likened it to “the conductor of a weather symphony” or an American football quarterback calling plays. Even though La Niña tends to follow a general pattern, L’Heureux points out that each event is different and other factors can influence the ultimate outcome. La Niña doesn’t typically have a major influence on weather in Europe, L’Heureux said.