The water was warm last summer as well. Around los angeles there were many warm water sightings: dorado, wahoo, scalloped hammerheads, green turtles, even a whale shark. One cause I heard was not el nino, but that a different mechanism kept the water warm in the 2013/2014 winter. That's certainly true again right now. SoI'd guess that 2015 will be like 2014. And the Solmar publishes video trip reports on their youtube channel. You might look at the trip reports from last may and see if it looks good.
We did Cocos during an el nino, and the hammerheads weren't schooling, we'd only see a few at a time. It was still an incredible trip.