GENEVA - The return of El Nino weather conditions are expected from as early as May this year, potentially affecting global temperatures and rainfall patterns, the World Meteorological Organization (WMO) said.

El Nino is a periodic warming of sea surface temperatures in the central and eastern Pacific Ocean, which typically lasts between nine to twelve months, according to the WMO.

A clear shift has been observed in the Equatorial Pacific, with sea-surface temperatures rising rapidly, suggesting a high likelihood of El Nino conditions developing between May and July this year, it said.

"After a period of neutral conditions at the start of the year, climate models are now strongly aligned, and there is high confidence in the onset of El Nino, followed by further intensification in the months that follow," said Wilfran Moufouma Okia, Chief of Climate Prediction at the WMO in a statement.

While models indicate a potential strong El Nino event this year, the WMO added that forecasts made during the spring are typically less reliable, and greater confidence in the predictions will be possible after April.

The weather pattern is known to disrupt regional climates, potentially bringing increased rainfall to southern South America, the southern United States, parts of the Horn of Africa, and central Asia, while causing drought in Australia, Indonesia, and sections of southern Asia. It can also have a warming effect on the global climate, the WMO said.

- Olivia Le Poidevin, editing by Kirsti Knolle/Reuters