El Nino, which affects wind and rainfall patterns, has been blamed for droughts and floods in countries around the Pacific rim over the past year.

The BBC's Simon Ingram reports: "severe drought and months of pollution"

It has caused tornadoes in Florida, smog in Indonesia and snow in Mexico.

The World Meteorological Organisation said El Nino was "in its dying stages" but their weathermen do not know yet how quickly it will fade away.

Computer simulations helped the weathermen predict El Nino's demise.

The WMO report says: "One model has conditions moving rapidly towards normal by mid-1998, and another has El Nino lingering on towards the end of the year."

El Nino caused forest fires in Brazil

But it also warns that a "La Nina" system, characterised by abnormally cold ocean conditions in the eastern equatorial Pacific, may follow.

It said forecasters were divided over whether there will be a return to normal weather patterns or another bout of disruption induced by La Nina, also known as 'cold tongue'.

La Nina brings reverse weather conditions - areas blighted by El Nino-generated drought, such as Southeast Asia, are lashed by unusually heavy rains.

Smog in Indonesia

Three computer simulations forecast a return to neutral conditions and five a La Nina episode by the end of the year, the WMO said.

The organisation's update said four conditions typical of El Nino are becoming less pronounced.

Those conditions are warming in the eastern Pacific Ocean; shifting of precipitation from the western to the eastern Pacific; slowing of trade winds; and changes in sea level.

El Nino causes changes in normal weather patterns, resulting in drought in usually wet areas and flooding in dry ones.