Through June, the eastern Pacific was warmer than average, but the lack of a strong gradient in sea surface temperature anomalies between the eastern and western Pacific may have kept the atmosphere from getting in sync with the developing El Niño.
You're not the only one wondering if we will see El Niño grow or continue into this coming winter 2015. How useful are March winds and subsurface temperatures across the tropical Pacific Ocean in predicting winter El Niño or La Niña states?