The WMO's latest forecast indicates that there is an 80 percent risk of El Niño occurring between June and August, and an even greater risk later in the year.
"We must prepare for a potentially strong El Niño - which will exacerbate drought and heavy rains and increase the risk of heat waves both on land and at sea," WMO Director-General Celeste Saulo said in a statement.
Exactly when El Niño will occur and how extensive it will be are more uncertain.
"The world must treat this as the urgent climate warning it is. El Niño conditions will add fuel to the fire in an increasingly warming world. The impacts will hit even harder, travel even further and cross borders with devastating speed," said UN Secretary-General António Guterres in a
.
El Niño is a warming of surface water temperatures in the Pacific Ocean off South America. It occurs every two to seven years and lasts for up to a year, typically leading to more rain in the southern United States and drier weather in Australia, Indonesia, southern Asia and southeastern Africa.
It has not been proven that climate change affects El Niño itself, but it can amplify the weather effects the phenomenon produces.
