Early signs suggest that Sydney could be drenched by a third year of La Niña misery

After two soggy summers in a row, not to mention some of the most widespread flooding on record, hopes were raised at the end of June when the Bureau of Meteorology announced that the La Niña weather event behind relentless downpours in 2020 and 2021 had officially ended. However, it now seems that this welcome declaration might have been premature and what’s more, the rains might well continue for another 12 months.

This would make the current La Niña a three-year event, which isn’t unheard of – Australia has recorded three such triple La Niñas since 1950. The conditions that drive this pattern of weather – increased rainfall driven by warmer waters pushed down from the equator by the trade winds, especially during the Southern Hemisphere summer – had appeared to wane in late June as Pacific Ocean temperatures began dropping. However, increased trade winds in the West Pacific threaten to trigger the sequence of conditions that create the kind of excessively wet summer the east coast has endured for the past two years.

Meteorologist Thomas Saunders took to Twitter to share the suspicious wind movements over the Pacific region that might be signaling a third year of rain. And that’s not the only thing causing weather-related worries. A negative Indian Ocean Dipole (IOD) is also forming, meaning there is a greater than average temperature difference between two areas in the Indian Ocean. This weather phenomenon hasn’t been officially declared yet, but the double whammy of a negative IOD and a La Niña has historically resulted in extreme rain events, including the downpours that caused 1974 to be the wettest year ever recorded in Australia (although it’s hard to image a wetter few years than the ones we’ve all just experienced).

A negative IOD and La Niña double event last occurred in Australia in 2010-11, which led to the wettest spring on record as well as devastating flooding in Queensland. While the Australian BOM is yet to formally declare a third year of La Niña, weather models from overseas have already suggested it's likely. A report released by the US National Weather Service in June stated that there is a 58-59 per cent chance of a La Niña developing between September and December this year, while Japan’s national meteorological agency put the chances of a third consecutive washed-out summer at 60 per cent. Frankly, we don’t like them odds.

The good news is there are still plenty of fun things to do in Sydney when it rains.