UC Irvine Professor Jin-Yi Yu, an Earth system scientist and a leading authority on global climate phenomena, indicates that the current El Niño event developing in the tropical Pacific Ocean for the 2026-27 winter season is projected to be exceptionally strong. According to Professor Yu, this event is very likely to surpass the intensity of the 2015-16 El Niño, which was previously the strongest observed in the modern era.
El Niño is a climate phenomenon characterized by abnormally high sea surface temperatures in the tropical Pacific Ocean. This warming typically extends over a vast area, covering up to two-thirds of the tropical Pacific, with temperatures rising one to two degrees Celsius above normal. Historically, Peruvian fishermen first observed this warming around Christmastime, leading to its name. The phenomenon usually begins to appear in the spring, grows significantly during the summer and autumn, and reaches its peak intensity in the winter months.
The current El Niño is already demonstrating considerable strength. While it has not yet reached its peak, which is anticipated in November, December, or January, the associated ocean warming is already substantial. Sea surface temperatures in the affected region are approximately two to three degrees Celsius warmer than normal. This level of warming already qualifies the event as a “very strong El Niño” in scientific terms, meaning temperatures are at least two degrees Celsius above normal.
Computer models project that the sea surface temperature in the Pacific region, where El Niño strength is monitored, will be three to five degrees warmer than normal. For comparison, the 2015-16 El Niño, which held the record for modern observations, was 2.7 degrees Celsius warmer than normal at its peak. This suggests the 2026-27 event is poised to exceed that benchmark. Professor Yu states that the scientific community is confident this event will be stronger than the 2015-16 El Niño. The remaining question, according to Professor Yu, is whether this event could even surpass the 1877 El Niño, which, if it occurs, would make it the strongest El Niño ever recorded.
For Southern California, a strong El Niño typically leads to specific weather impacts, particularly during the winter. Past El Niño events have historically resulted in heavy rainfall across the Southwestern United States. The current strong El Niño has already been linked to high surf and tides, which have caused significant erosion along the Southern California coastline. As the event strengthens, its impact on California’s winter temperature and rainfall is expected to become more pronounced. UC Irvine researchers are actively studying these potential outcomes for 2026 and 2027.
Various departments at UC Irvine are engaged in understanding and preparing for the El Niño’s effects. Earth system scientists are utilizing computer simulations to predict specific outcomes. Environmental engineers are preparing to monitor the impact of the phenomenon on critical infrastructure, local beaches, and inland regions prone to flooding. Public health researchers at UC Irvine are also providing guidance to Southern California residents on how to protect themselves and their families during the changing weather conditions. Other experts at the university are examining the climate phenomenon from economic, cultural, and humanitarian perspectives.
As the El Niño continues to develop, its peak intensity is expected in the coming winter months. The full extent of its impacts on local conditions, including rainfall and coastal stability, will become clearer as the season progresses.
