A LA Nina event is now "more likely than not" to occur this year, according to the Bureau of Meteorology.
BOM climate prediction services manager Dr Andrew Watkins said if recent trends in Pacific climate patterns continued, a La Niña event would be established before the end of winter.
The main feature of a La Nina is a broad region of colder than average water centred along the eastern equatorial Pacific.
"Computer model forecasts show a significant likelihood of a La Niña in 2010", Dr Watkins said.
However the bureau said it was still possible that recent trends may stall without La Nina thresholds being reached.
Even if this did occur, parts of Australia may still experience wetter than average conditions, especially if the Southern Oscillation Index remained positive.
The surface of the equatorial Pacific was currently cooler than average in some areas, while the Southern Oscillation Index, which was often indicative of pressure patterns over Australia, had been positive since April.
The current value of the SOI was around +6.
