This winter, weather watchers on the Chinese mainland have their eyes on the Pacific. In October 2025, the Chinese mainland’s National Climate Center confirmed that sea surface temperatures in the central-eastern equatorial Pacific have dipped below -0.5°C—a threshold meteorologists call a La Niña state.
La Niña refers to a sustained cooling of sea surface waters that can reshuffle weather patterns worldwide. To track it, experts use the Nino 3.4 index. When this index falls under -0.5°C for at least five consecutive months, meteorological agencies recognize a full La Niña event. As of now, the waters are cool enough to signal La Niña conditions, but they haven’t stayed cold long enough to trigger an official event.
Why does this matter? La Niña can influence winter temperatures, rainfall and even snowstorms across Asia, Europe and North America. Residents and businesses—from farmers to ski resorts—often watch these indicators to plan ahead.
Digging deeper, the Zhejiang Provincial Climate Center points out that La Niña events occur every two to seven years. However, global warming is adding complexity, increasing the frequency of these cooling episodes. Earlier in 2025, a weak La Niña wave left cold subsurface waters stacked beneath the Pacific's surface, making a return to La Niña conditions by year-end more likely.
That cycle has sparked chatter about a double La Niña—two La Niña winters in a row. But experts clarify that the term refers to consecutive winters, not two events within one year. And according to the latest forecasts from the National Climate Center, the chance of back-to-back La Niña winters in 2025-26 remains low.
As the season unfolds, climate watchers will keep monitoring Pacific temperatures and Nino 3.4 readings. For now, it seems we’ll dodge a double dose of La Niña, but the early signals remind us how interconnected our global climate really is.
Reference(s):
China enters La Nina state, but 'double La Nina' unlikely this winter
cgtn.com
