The WMO said the chance of a full-fledged El Niño event between December 2018 and February 2019 is estimated to be about 75-80 percent, and about 60 percent for it to continue through February to April 2019.
U.S. weather forecasters also said there's a high chance of a El Niño forming. "Sea surface temperatures in the tropical Pacific were comfortably above the threshold for El Niño in October 2018, but the atmospheric response is lagging. A deep pool of warm water is available below the surface to renew and sustain the surface anomaly, however, and forecasters estimate an 80 percent chance of a weak El Niño during Northern Hemisphere winter 2018-19," according to Climate.gov.
El Niños are not caused by climate change, but researchers have previously suggested that we could experience extreme El Niños more frequently as our planet continues to warm.