Key points
- Weather agencies predict a 60-71% chance of a La Niña event later this year.
- The Bureau of Meteorology says that if La Niña occurs it will be relatively weak and short-lived.
- La Niña can bring increased precipitation, cooler temperatures and more tropical cyclones.
While international weather agencies predict the return of La Niña before the end of the year, the Bureau of Meteorology (BoM) has made its contribution.
Both La Niña and its counterpart, El Niño, result from changes in ocean temperature in the tropical Pacific and have a strong influence on climate.
La Niña occurs when winds become stronger, changing ocean currents and drawing cooler water from below.
La Niña events can lead to increased precipitation and cooler daytime temperatures. They can also mean more tropical cyclones, a greater chance of flooding and an earlier start to the monsoon.
In early September, the World Meteorological Organization predicted a 60% chance of La Niña conditions later this year.
The US-based forecasting institute, the National Oceanic and Atmospheric Administration, said this month there is a 71% chance that La Niña will emerge between September and November, adding that it is expected to persist until January- March of next year.
Many other US meteorologists also say La Niña is likely.
What did the Bureau of Meteorology say?
On Tuesday, the BoM shared an update saying that while “some atmospheric indicators such as pressure, cloud and trade wind patterns over the Pacific have been more La Niña-like in recent weeks,” it remained to be seen whether or not those conditions would continue.
“It is possible that La Niña could develop in the coming months, but if so, it is expected to be relatively weak (in terms of the strength of the sea surface temperature anomaly) and short-lived,” he added.
Earlier this month, Steven Bernasconi, the BoM’s head of risk preparedness and response, told reporters the bureau was at La Niña “watch” level, with three of seven indicators pointing to the climate event in progress.
“Watch” status indicates a 50% chance of La Niña developing.
The BoM’s assessment is based on climate model predictions and atmospheric and oceanic conditions in the Pacific.
Another La Niña in 2024 would mark the fourth such event in five years. On average, La Niña events have occurred every three to seven years in the past.
With additional reporting from the Australian Associated Press