A wet start to 2025 is likely for Australia thanks to the return of La Nina conditions in the Pacific Ocean. The great rainmaker's summer arrival is unusual and has swung the outlook to favour above average rain for the coming months.
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00:00Finally, the second time since 1950, La Niña is emerging in the middle of summer.
00:07Thousands of kilometres off Australia's east coast, the water temperature in the central
00:10Pacific Ocean has now dropped around one degree below average.
00:14And that passes the La Niña threshold for the first time since the triple dip event
00:18from 2020 to 2022.
00:20If La Niña conditions prevail for another two months, it officially becomes the fourth
00:24event in five years, a frequency only observed twice previously since 1900.
00:30The cooling of the sea surface increases the difference in water temperature between the
00:34central and the west Pacific, an imbalance which strengthens humid easterly winds blowing
00:39towards Australia, promoting the development of cloud and rain over our longitudes.
00:44However, La Niña typically forms in winter and has its greatest impact in spring, when
00:49national average rainfall increases by 49 per cent.
00:53That figure falls to a 20 per cent boost through the summer and the autumn.
00:57The historical swing to favour rain is also reflected in the Bureau's latest seasonal
01:02outlook – up to an 80 per cent chance of above-medium falls through northern and eastern
01:06parts of the country across the next three months.
01:09But this addition of La Niña could be short-lived.
01:12Long-range modelling currently tips our rainfall will return to normal by the middle of autumn.