El Niño/La Niña Update (December 2009)

An El Niño event, which started in June 2009, is well established across the 

tropical Pacific. El Niño conditions are very likely to continue at least through the 

remainder of 2009 and into the first quarter of 2010. Some climate patterns typical 

of El Niño have been observed over the last several months. The expected 

continued presence of El Niño into early 2010 has implications for many climate 

patterns around the world over the next several months, keeping in view the fact 

that, in some regions, impacts typically continue during the decay phase. Decay of 

the El Niño event to near-neutral conditions across the tropical Pacific during the 

approximate March-May 2010 period is considered the most likely further 

development. The possibilities of a second year of El Niño conditions or rapid 

transition to a La Niña situation are considered unlikely at this time.