13 January, 2022
La Niña - what is it?
Late November, the Bureau of Meteorology (BoM) declared that a La Niña has developed in the Pacific Ocean.
But what exactly is a La Niña? And what
does it mean for us?
La Niña is part of a cycle known as the El Niño-Southern Oscillation (ENSO), “a naturally occurring shift in ocean temperatures and weather patterns along the equator in the Pacific Ocean”, according to the BoM.
“During La Niña, waters in the central
or eastern tropical Pacific become
cooler than normal, persistent south-east
to north-westerly winds strengthen in the
tropical and equatorial Pacific, and
clouds shift to the west, closer to
Australia,” said the BoM.
Typically, during La Niña events,
rainfall becomes focused in the western
tropical Pacific, leading to a wetter than
normal period for eastern, northern, and
central parts of Australia.
“La Niña also increases the chance of
cooler than average daytime temperatures
for large parts of Australia and can
increase the number of tropical cyclones
that form,” said BoM’s head of operational
climate services, Dr Andrew
“La Niña is also associated with earlier
first rains of the northern wet season,
as we’ve observed across much of tropical
Australia this year. The last significant
La Niña was 2010–12. This strong
event saw large impacts across Australia,
including Australia’s wettest two-year
periods on record, and widespread flooding.
“La Niña also occurred during spring
and summer of 2020-21. Back-to-back
La Niña events are not unusual, with
around half of all past events returning
for a second year.”
Dr Watkins said that this year’s event
is not predicted to be as strong as the
2010-12 event and may even be weaker
than in 2020-21 La Niña event.
Essentially, we are looking at having
a wetter, and slightly cooler summer than
According to the BoM’s summer outlook,
it shows that eastern Australia is
likely to be wetter than average, with an
increased risk of tropical cyclones, heavy
rainfall, and widespread flooding.
is currently no strong swings to either
wetter or drier conditions in South
Australia, while parts of Western
Australia are likely to see average, to
slightly above average rainfall.
It seems like mighty Gilgandra might just miss the full brunt of La Niña, but do expect more than usual rainfall, that’s not going anywhere any time soon.