The El Niño/Southern Oscillation (ENSO) phenomenon is a periodic fluctuation of sea-surface temperatures and atmospheric pressure across the tropical Pacific Ocean. During the El Niño phase of the cycle, the eastern tropical Pacific Ocean warms substantially. This can cause significant short-term increases in global-average surface temperatures, and through atmospheric teleconnections, a strong El Niño event can affect weather patterns around the globe. A particularly strong El Niño emerged during the winter/spring season of 2015/2016, rivaling the major El Niño of 1998. Using a state-of-the-art seasonal forecasting and research tool, USGCRP agencies successfully forecasted the event six months before it occurred, providing advance warning of potentially disruptive shifts in weather and climate patterns.

Based on models from NOAA, DOE, NSF, NASA, and other modeling centers, the North American Multi-Model Ensemble (NMME) produces skillful short-term (intraseasonal to interannual) climate forecasts on a routine basis. El Niño forecasting aids decision makers in many different industries, including agriculture, water-resources management, public health, emergency management, and national security, who stand to benefit from more accurate forecasts of climate extremes. NMME seasonal forecasts are disseminated via NOAA’s National Weather Service and U.S. Drought Outlook.