Water temperature off the West coast are often a function of the wind direction.  If the winds blow more dominantly from north-to-south (northerly) then Ekman transport means that surface water will move away from the coast, and allow colder, deeper water to upwell to the surface.  The last month or so has been characterized by a big anomalous ridge in the N. Pacific (very La Nina-like, btw), which may have contributed to more northerly winds and cooling