La Niña, where the water is cooler than normal, is indicated by blue colors .
La Niña, where the water is cooler than normal, is indicated by blue colors . Notice the very cool water (blue) in 1988-1989, near the top of the plot, which was a very strong La Niña.  Notice the cool water in 1995, 1998, 2007 and 2011, which were La Niña years.  La Niña events occur after some (but not all) El Niños.