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."

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.