The biggest area of anomalous warmth in February was the Arctic, which also had record - low sea ice levels during January and February. (wxshift.com)
The second conundrum with this explanation is that, while El Nino typically does perturb the winter Northern Hemisphere jet stream in a way that favors anomalous warmth over much of the northern half of the U.S., the typical amplitude of the warming (see Figure below right) is about 1C (i.e., about 2F). (realclimate.org)
Until 2014, persistent and increasingly anomalous warmth in the tropical West Pacific Ocean (near Indonesia) had been in place for the better part of two decades — not coincidentally since the last big El Niño event in 1997 - 1998. (weatherwest.com)