El Ninos bring dry weather, and potential drought and tropical cyclone conditions.
The Australia Bureau of Meteorology says the Pacific Ocean has been warming along the equator over recent weeks, and continued warming is expected in central Pacific in coming months.
Reduced rainfall in Fiji is already pointing to El Nino patterns.
For Australia, El Nino is usually associated with below average rainfall.
Since 1990, around two-thirds of El Nino events there have caused major droughts.
Meteorology and climate adviser to the Pacific Regional Environment Programme, Neville Koop, says Pacific islanders will need to prepare for the impacts of dry weather from December onwards.
“The very insidious thing about El Nino is they creep up quite slowly and before you really know, it’s upon you, the problems have set in,” he told Pacific Beat.
“In this case it’s drought, it’s lack of rain.
“If we start engaging some simple water management practices right now, we’ll find ourselves in a better situation later on when the dry weather really starts to bite.”