What To Expect From El Niño and La Niña?

As a strong El Niño phenomenon is being predicted for the coming months, large parts of the United States can potentially expect a wet and stormy fall and winter. This is seen in data from the International Research Institute for Climate and Society at Columbia University. While El Niño can also bring excess rain to parts of South America, Central Asia and Africa, it can exacerbate drought conditions in places like the Pacific Northwest, the Amazon, Central America and Southern Peru. Climatic conditions during La Niña, on the other hand, are predictive of increased rainfall on the northern coast of South America, in Central America and in the Caribbean and dryer periods in the Southern U.S., Chile, Argentina, Uruguay and southern Brazil.

El Niño and La Niña are both a part of the global climate cycle known as the El Niño-Southern Oscillation (ENSO). El Niño is produced by the warming of the equatorial Pacific waters, while La Niña is what happens when these waters are cooling below their average temperatures. During El Niño, trade winds over the Pacific normally moving from east to west weaken or even cease and reverse, making hot Pacific water accumulate near the Pacific coast of the American continent, causing rains and floods in the United States. La Niña meanwhile strengthens these trade winds, pushing warm ocean water towards Asia. If the temperature anomaly the El Niño/La Niña reference area is a maximum of 0.5° Celsius above or below its averages, neutral conditions prevail. Both phenomena normally peak late in the year.