The latest El Nino weather phenomenon, which was one of the most powerful on record, has ended but could be replaced by its stormy sister La Nina in the coming months, the UN meteorological agency said Thursday.

"Atmospheric indicators that had shown strong El Nino patterns early in 2016 returned to near-average in June and July," the World Meteorological Organization said.

El Nino affects rainfall patterns and causes both drought and flooding.

As it recedes the Pacific cooling trend known as La Nina typically begins, often causing increased rainfall, storms and snow across the globe.

"A La Nina event may develop in the third quarter of this year, but it is likely to be weak," the WMO said. "It is not expected to match up to the moderate to strong La Nina of 2010-2011."

The first six months of this year were the hottest on record, setting 2016 to be the hottest year despite the likely development of a La Nina pattern.

El Nino occurs every four to five years.

The latest version has already left 60 million people worldwide requiring "urgent assistance," particularly in Africa, Stephen O'Brien, UN under-secretary general for humanitarian affairs and relief, said in April.