Will El Niño 2015 rival the strongest year on record?

What is El Niño and what causes one?

July 2015

The waters of the eastern Pacific Ocean are heating

up, scientists say, building towards a strong El Niño event that could rival the intensity of the record 1997 event that wreaked weather-related havoc across the globe, from mudslides in California to fires in Australia.

According to the latest forecast released Thursday by NOAA's Climate Prediction Center, this year's El Niño is "significant and strengthening."

"There is a greater than 90% chance that El Niño will continue through Northern Hemisphere winter 2015-16, and around an 85% chance it will last into early spring 2016," the NOAA said in a statement.

The weather phenomenon largely became a part of the public vernacular during the 1997 El Niño. It caused devastating flooding in the western U.S. and drought in Indonesia. It was blamed for deadly virus outbreaks in Africa and rising coffee prices around the world.

Chris Farley became El Niño personified on Saturday Night Live.

Pure chaos. But what is El Niño, and what impact will it have this time around? Let us explain.

El Niño is a warming of the eastern Pacific Ocean, mainly along the Equator -- see the thick red belt in the satellite photo, which indicates waters that are warmer than normal.

These warmer waters are normally confined to the western Pacific by winds that blow from east to west, pushing the warmer water toward Indonesia and Australia.

But during an El Niño, the winds slow down and can even reverse direction, allowing the warmer water to spread eastward all the way to South America.

El Niños occur every two to seven years in varying intensity, and the waters of the eastern Pacific can be up to 4 degrees Celsius (7 degrees Fahrenheit) warmer than usual.