US scientists on Thursday said that the El Nino warming trend of the Pacific Ocean waters has returned, bringing with it almost certain changes in weather patterns around the world.

The El Nino climatological effect -- the periodic warming of central and eastern tropical Pacific waters -- occurs on average every two to five years and typically lasts about 12 months.

The US National Oceanic and Atmospheric Administration said in a statement that the current El Nino was likely to develop further during the next several months, with additional strengthening possible and is expected to last through early 2010.

In past years, El Nino has been known to suppress Atlantic hurricane activity and typically brings beneficial winter rain to the arid US southwest.

But the weather system also often brings damaging winter storms in California and turbulent weather across the southern United States.

El Nino also has been associated with severe flooding and mudslides in Central and South America, and drought in Indonesia.

Jane Lubchenco, US undersecretary of commerce for oceans and atmosphere and NOAA administrator, said the agency plans to provide frequent updates to "industries, governments and emergency managers about weather conditions El Nino may bring, so these can be factored into decision-making and ultimately protect life, property and the economy."