The current El Nino weather pattern in the Pacific Ocean looks increasingly likely to be followed with an immediate reversal back to a La Nina, correlated with wetter conditions in Australia, in the spring according to a range of international long-term weather forecasters.
While Australia's official forecaster, the Bureau of Meteorology (BOM), does not produce outlooks that far out, agencies such as the International Research Institute (IRI) for climate have quietly been ratcheting up the chances of La Nina.
In its most recent update IRI, based at the University of Columbia in the US, made a big shift in its outlook for the Australian spring, raising the chance of a La Nina from 45 per cent to 65pc.
La Nina events often form in the Australian winter, but IRI's models suggest it could be later this year, with a 45pc chance of it developing during May, June or July.
Veteran forecaster Don White said it was difficult to predict weather outlooks so far in advance but added a number of reputable meteorological organisations were raising the possibility of La Nina.
"I don't think we'd see a full reversal to La Nina by early winter given the El Nino is still in place, but these agencies will be looking at trends in sea surface temperatures and subsea surface temperatures and they may be getting a signal that looks like a La Nina could form," Mr White said.
A BOM spokesperson said at this stage it was too soon to forecast a La Nina event in 2024.
They said historically, La Nina has developed around 40-50 per cent of the time after an El Nino. La Nina tends to begin closer to autumn generally, which forecasters believe is unlikely this season.
The 65pc chance of La Nina forecast from IRI is markedly higher than normal.
The BOM spokesperson said around half of the years since 1900 have been either La Nina or El Nino. La Nina occurs on average every three to seven years.
However, if a La Nina does form it will be the fourth in five years.
The current El Nino is forecast by the BOM to continue through to autumn.
However, Mr White said while there were El Nino conditions in the Pacific there were a number of anomalies that potentially could have been a factor in the heavy rain seen over summer over much of northern and eastern Australia.
"We've got a number of things with the current El Nino in regards to ocean temperatures, particularly in the western Pacific, that have been atypical, with moisture feeds developing and flowing over Australia," he said.
"It is important to remember that these labels don't dictate the weather, just increase the odds of above or below average rainfall accordingly, we get a bit caught up in absolutes."
Mr White said the correlation was actually stronger between temperature than rainfall.
"El Nino has a higher correlation with above average temperatures than below average rainfall."