March 12, 2014

El Niño Can Affect The World’s Weather

Q:  It’s in the news that an El Niño may form this summer. What is the difference between an El Niño and La Niña?

a palm tree bends during a storm

An El Niño can mean wet conditions in some areas, but dry in others. Photo: Shutterstock

A: The main difference between the two involves water temperature, explains John Nielsen-Gammon, a weather expert at Texas A&M University. El Niño and La Niña – Spanish for “the child” – both occur in the central Pacific Ocean. “During an El Niño event, which can last almost a year, the waters in that region are warmer than usual,” he says. “The opposite occurs during a La Niña – the waters tend to be cooler than usual. But the important thing is that both events can affect weather patterns in the United States and around the world.”

Q: How do they change our weather?

A:  In years when a La Niña occurs, there are often warmer and drier conditions in many areas, including Texas, Nielsen-Gammon says. “In general terms, a La Niña period means drier weather patterns for Texas. There have been numerous studies on how El Niño and La Niña affect weather patterns, and specifically, hurricanes and their intensity. Some research indicates that the sorts of hurricanes that affect Texas are more common during La Niña periods than during a neutral or El Niño year. We do know that an El Niño can last up to 18 months and it can influence weather everywhere, so when one forms, there is naturally a lot of interest in what will happen.”

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Weather Whys is a service of the Department of Atmospheric Sciences at Texas A&M University.

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