Likely emergence of La Nina this fall, potentially leading to severe weather conditions in Korea.

The Korea Meteorological Administration (KMA) has predicted a possible La Nina event this fall, and the World Meteorological Organization (WMO) estimates a 55% chance of La Nina forming between September and November, rising to 60% from October to December.

La Nina is a large-scale climate pattern characterized by sea surface temperatures in the central and eastern parts of the Pacific Ocean falling at least 0.5 degrees Celsius below average for five consecutive months. This cooling of the Pacific waters can lead to significant changes in weather patterns around the globe, including in South Korea.

According to the KMA, if La Nina forms, South Korea is expected to experience frequent and extreme weather swings. Hot and humid southerly winds would be more frequently brought into Korea, triggering frequent rainfall. However, drier conditions may begin to be observed from November.

In recent years, these overlapping influences have led to unusually warm or wet Novembers in Korea, despite a La Nina signal. This year, Korea may experience warmer-than-usual conditions in September and October, followed by colder conditions in November.

The KMA's weather forecast models predict a 54% likelihood of La Nina in September, rising to 68% in October and 57% in November. The probabilities of neutral conditions stand at 45% and 40% respectively, according to the WMO.

The KMA plans to work with the WMO for continuous observation and analysis of the La Nina weather event as fall grows nearer. If typhoon paths are altered, excessive rainfall could also occur, heightening flood hazards. La Nina may cause exceptions due to overlapping influences with the sea levels at the Arctic and sea surface temperatures in the Indian and Atlantic oceans.

La Nina is the opposite phase of El Nino, which is marked by unusually warm Pacific waters. While El Nino can lead to dry conditions in South Korea, La Nina can bring more rainfall. However, the specific impacts of La Nina on South Korea's weather are difficult to predict with certainty due to the complex interplay of various climate factors.

The International Research Institute for Climate and Society (IRI) indicated the probability of a La Niña development in South Korea between September and December 2025. They forecast a 39% probability for September-November and 44% for October-December 2025. As sea surface temperatures in the central tropical Pacific drop with the La Nina phenomenon, rainfall is reduced over the North Pacific region between September and October.

As the fall approaches, it is important for South Koreans to stay informed about the developing La Nina event and the potential impacts on their weather. The KMA and WMO will continue to monitor the situation and provide updates as more information becomes available.

Likely emergence of La Nina this fall, potentially leading to severe weather conditions in Korea.