Perth sweltered through its hottest January on record and the Pilbara town of Onslow surpassed 50 degrees to equal the nation’s highest temperature. Perth also had a record-breaking number of days above 40, with 13 so far this summer. The previous record was seven, in 2015-16.

South-western Western Australia also experienced severe bushfires. Central Australia experienced record-breaking rains this season, bringing to life seasonal rivers in western Queensland, the Todd River in the Northern Territory and Lake Eyre.

La Nina peaked in January and is now weakening, although it is likely to persist into the start of autumn and then is likely to return to a neutral pattern, although this won’t be properly established until autumn is under way.

Mr Domensino added that another driver behind the above-average rainfall had been the marine heatwave off the Tasman Sea, which had seen an increase in sea surface temperatures.

Along parts of the NSW coastline, sea temperatures inched towards record-breaking highs, driven by the broader effects of climate change, La Nina, the East Australian Current and localised southerly winds that push warmer water onshore. On Wednesday, Sydney ocean temperatures hit 26 degrees, higher than the monthly average of 24.7 degrees.

University of NSW professor of oceanography Moninya Roughan said this year could be in the top 5 per cent over the past 30 years, with satellite data placing temperatures above 26.5 degrees.

“It has been a very hot summer in the ocean. During January, off Sydney, the main body of heat moved offshore, and it was hot well offshore, but not so hot by the coast during the latter part of January. By February the warm water, known as the East Australian Current, moved back on shore, bringing very hot water to the coast,” she said.

Professor Roughan and her team have been measuring the waters off Sydney’s coast as part of Australia’s Integrated Marine observing system, with data stemming back 14 years.

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“In keeping with the movement of the current on and offshore, December was the hottest December on record, January was not particularly hot at the outer shelf region, but February was very hot,” she said.

December 23 was 5.56 degrees above average and an all-time December record of 25.7 degrees at a 25-metre depth. Meanwhile, February 3 hit an all-time record of 26.9 degrees.

“I was shocked at how hot it was and how unusual it is,” she said. “This region is warming faster than most regions on earth. It’s roughly two to three times the global average. These temperatures are extreme and we have broken a lot of records this summer; it is really, really sad.

NSW Rural Fire Service Deputy Commissioner of Field Operations Peter McKechnie said that, while this bushfire season had been quiet due to the above-average rains, there had still been a lot of grass fuel loads. He added there had still been significant grass and bushfire this season, burning through 90,000 hectares, a sizeable increase to the 30,000 hectares burnt during the 2020-21 season.

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“Whilst conditions have been very good for us and farmers, we’ve seen a lot of grass growth and, if we don’t maintain above-average rainfall over the coming months, there is a real danger in western NSW,” he said. “We need to be prepared going into next year if the grass growth continues. The fire seasons are going for longer. We can’t hide from the fact that they are starting earlier and finishing later.”

The Bureau of Meteorology’s official summer climate summary will be launched next week, at the end of the calendar month.

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