The Southern Oscillation Index tracks differences in air pressure between the eastern and western sides of the tropical Pacific.

El Niño and La Niña conditions occur when abnormally warm or cool waters accumulate in tropical latitudes of the central and eastern Pacific Ocean. The Oceanic Nino Index is the tool NOAA scienitsts use to watch for these temperature changes. 

How El Niño is like different flavors of ice cream.  Seriously.

The forecasts often provided useful information for the coming few months, but had more limited accuracy and value in forecasting beyond that.

June 2009 SST anomalies

As of late August 2014, tropical atmospheric temperatures appear to be responding more strongly to the ocean than they typically do at this early stage of El Niño development.   

If you are someone who wants more or stronger ENSO events in the future, I have great news for you–research supports that. If you are someone who wants fewer or weaker ENSO events in the future, don’t worry–research supports that too.

sea-surface height from satellite data

Forecasters are still calling for a 65% chance of El Nino conditions being met in the next few months. Isn't this late for the start of an ENSO event? 

2003 CA fire

El Niño could bring increased rain to California. How might this affect the threat of wildfire?

Along with ENSO, what other climate patterns might be useful for predicting temperatures and precipitation in the United States?

OLR anomalies in 2012 versus 2014

Where is El Niño?  How is this year different from 2012 when El Niño was predicted, but never arrived?  

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