Australia could be heading into another El Niño year according to new analysis by the Bureau of Meteorology, which found the chance Australia would be affected by the phenomenon in 2017 had increased to 50%.

Six of the eight models used by Australian climatologists to predict El Niño and La Niña events indicate the El Niño threshold could be reached by July, while seven indicate a steady warming in the Pacific Ocean over the next six months.

El Niño is declared when temperatures in the tropical Pacific Ocean are 0.8C above average, and brings a dry winter and spring to southern Australia and a warmer than average spring and summer to the eastern states.

It comes as the Bureau of Meteorology (BoM) confirmed Sydney had just experienced its hottest summer on record, with mean temperatures 2.8C above the long-term average.

Sydney experienced a record-breaking 26 days of 30C or higher and 11 days of 35C or higher.

In 2015 Pacific Ocean temperatures increased to 2C above average, causing the most severe El Niño since the late 1990s.

BoM manager of climate prediction services, Dr Andrew Watkins, said it could mean a return to difficult conditions for Australian farmers after what he described as a “neutral” year in 2016, which produced the best season in decades for Australian grain growers.



“We have been seeing a fairly steady warming up of those waters [in the tropical Pacific Ocean] since the start of the year,” Watkins said.

The trend is significant enough to place Australia on El Niño “watch”, which occurs when the chance of El Niño rises to 50%. In any given year the chance of El Niño sits at 25%, Watkins said, so a watch status means it is twice as likely to occur.

If the probability increases to 70%, which would usually be accompanied by a warming of at least 0.5C, the status will be upgraded from “watch” to “alert”.

However Watkins said the models used to predict the trend are less accurate in autumn, because “that’s typically the time of year where events break down or develop.”

“There can be fairly rapid changes at times, the Pacific is most volatile at this time of year,” he said.

Watkins said the number of El Niño events had increased in recent years, but that should not be read as a trend, saying the 20th century showed a number of “clustered” El Niño and La Niña events, surrounded by years of relative steadiness.

Since 2006 Australia has experienced two years of El Niño and two of La Niña, but the former were more severe.