If you thought the end of La Niña meant the end of the wet weather season in Australia, you would be wrong. The Bureau of Meteorology has announced we are experiencing a negative Indian Ocean Dipole (IOD) event, meaning there’s more rainy weather on the way.
What is the Indian Ocean Dipole?
The Indian Ocean Dipole is one of Australia’s main climate drivers.
It is determined based on the difference in sea surface temperatures between two poles – one in the western Indian Ocean and another in the eastern Indian Ocean.
The IOD’s main influence is on rainfall. During a positive event, warmer sea surfaces in the western Indian ocean can combine with easterly wind anomalies to cause less cloudiness and less rain in Australia.
The last time we saw a positive IOD event was in 2019, which many will remember as the summer with some of the worst bushfires in history and very little rain to cool them down.
During a negative IOD event, we’ll see cooler sea surface temperatures in the western Indian Ocean with westerly winds that bring more clouds and extra rainfall to the top end and southern Australia. This is what BOM has announced has been established now.
How will it impact Australia?
As mentioned, a negative IOD often indicates a higher chance of average rainfall across the country.
In the latest climate outlook, the Bureau of Meteorology predicts that rainfall in the months of August, September and October is likely to be above median for most of the country.
The last time a negative IOD was in effect was five years ago in 2016. As the ABC reports, the winter of 2016 was one of the wettest on record with a May to September period that broke historic rainfall totals.
Experts predict this IOD event will not be as severe as the one in 2016. Still, it’s best to keep an umbrella on you for the next few months.