A few weeks ago, the Australian Bureau of Meteorology declared that the Pacific Ocean is no longer in an El Niño state and has returned to “neutral.” American scientists at the National Oceanic and Atmospheric Administration have been more hesitant, but they estimate that there is an 85% chance that the Pacific will enter a neutral state in the next two months and a 60% chance that a La Niña event will begin by August. … As an El Niño phase begins, [the trade winds] winds weaken, so that warm sea surface temperatures move east toward South America. This can cause climatic shifts across the globe: landslides in Peru, drought in Australia, fish die-offs in the eastern Pacific and more frequent atmospheric rivers in Southern California. These changing weather patterns also weaken the trade winds further, leading to more warm water off the coast of South America, which in turn weakens the winds, and so on.

Related El Nino/La Nina story: 

• Capital Press: Climatologists expect La Nina to return before summer ends