Australia’s winter of 2023 was the warmest since official records began in 1910, with average daily temperatures 1.53C above the long-term average.
According to data from the Bureau of Meteorology released on Friday, the 2023 winter beat the previous record of 1.46C above the average set in 1996. Every winter since 2012 has been warmer than the 30-year average calculated from 1961 to 1990.
Global heating and weather conditions that delivered sunny days were behind the record, scientists said.
For maximum temperatures, the 2023 winter was 1.85C above average, ranking second behind the mark of 1.94C set in 2017.
The Australian winter is June, July and August. Over the past two decades, only the winters of 2012 and 2007 have been below average for temperatures.
The eastern region of the continent was particularly hot this year, with the temperature 2.03C above average – easily beating the previous record of 1.66C set in 2013. Queensland, Tasmania and New South Wales all experienced their hottest winters on record, with all other states and territories seeing temperatures in the top 10 years for heat.
Dr Simon Grainger, a senior climatologist at the bureau, said there were two reasons for the winter heat. High-pressure systems had sat over much of the continent’s south-east, bringing sunnier and drier conditions. Global warming was also a factor, he said.
The record winter comes as large parts of the country were warned last week to expect an increased risk of springtime bushfires. Scientists are concerned an expected El Nińo climate pattern that increases the chances of hotter and drier conditions could bring a dangerous summer of bushfires.
Dr Andrew King, a climate scientist at the University of Melbourne, said the winter warmth was “pretty consistent with the trend towards warming that we have already seen and expect to continue as we keep emitting greenhouse gases”.
King said the high-pressure systems that brought the extra warmth were “part of the story”, adding “we would not get the temperatures that we have seen this winter really happening without human-caused climate change”.
Australia’s weather bureau has stopped short of declaring an El Nińo, despite the World Meteorlogical Organization and the US National Oceanic and Atmospheric Administration both stating the system is in place.
In Australia, El Nińos increase the risk of hotter and drier conditions, particularly over the more populated eastern side of the continent.
El Nińos are linked to higher than average sea surface temperatures in the equatorial Pacific but while those conditions are present, the bureau has said it has not yet seen a consistent weakening of the east-to-west trade winds that are also typical of the climate pattern.
The bureau says there is still a 70% chance of an El Nińo locking into place this year. The BoM is also predicting a potential positive Indian Ocean Dipole – a phenomenon that sees warmer water in the Indian Ocean move away from Australia’s north-west that can lead to drier conditions.
On Thursday, the bureau said Australia’s spring would likely see hotter than average temperatures and lower than average rainfall – a combination that would increase the risk of bushfires.
Dr Masoud Edraki, a senior hydrologist at the bureau, said the record-high sea surface temperatures seen globally would continue to affect Australia’s weather.
“We know that a warmer climate does increase the risk of extreme weather including heatwaves and drought,” he said.
“We are already seeing longer fire seasons, and an increase in the number of dangerous fire weather days over most of Australia. We don’t know yet how global warming, and particularly the increased warmth in the oceans, is affecting our typical climate drivers.
“Our climate forecast model is consistent with the international climate forecasts that show Australia is trending dry and warm for the coming season, particularly in the south-west and much of south-eastern Australia.”