Winter is coming … even though it may not feel like it.
With Thursday marking the first day of winter, much of Australia can look forward to a warmer-than-average season, after a historically cold May for much of the east coast.
The Bureau of Meteorology’s winter outlook points to temperatures across the country being warmer and conditions drier than median figures, from June to August.
As ocean temperatures approach El Niño thresholds, minimum temperatures will also likely be above average, with only parts of eastern South Australia and western New South Wales the exceptions.
The BoM winter outlook shows the likelihood of higher-than-average temperatures in July, which is expected to be warmer than June.
A positive Indian Ocean dipole is forecast with the potential El Niño weather event, with Weatherzone meteorologist Ben Domensino saying it would lead to both warmer days and colder nights.
“Those are two climate drivers that promote dry and warm weather in Australia during winter. So with those external broadscale forces at play, we’re most likely looking at drier-than-average weather for most of Australia and warmer-than-average days, but colder-than-average nights.
“Because if they do both develop, they’ll be reinforcing each other and the impacts would be widespread. Mostly inland areas have the strongest influence from El Niño and the Indian Ocean dipole,” he said.
The areas that will face the steepest drops in overnight temperatures will be the Murray-Darling Basin and inland areas of central and western Australia.
“The dry weather in the clear skies usually allows more radiative cooling to occur. So overnight temperatures are typically lower than average and that can mean more widespread frost and more severe frost than a normal winter,” he said.
The same can be expected for Sydney, with mid-to-high 20s expected during winter days.
The warmer temperatures come after Australia’s east coast shivered through a month of abnormally cold nights, with Sydney and Brisbane recording some of their coldest May temperatures on record.
Records were broken in Amberley in south-east Queensland, where the average minimum temperature in the past month was 5.2C, well below the long-term May average of 10C and the lowest May minimum temperature recorded there since 1942.
Brisbane airport recorded an average minimum of 10.6C, which is the coldest May on record, with data stretching back to 1950.
In Sydney, both Observatory Hill and Richmond airport recorded their lowest minimums in May since 1957.
“It’s very unusual to see overnight temperatures this cold in May,” Domensino said.
“It normally is a time of year where we start to see nights becoming colder over eastern Australia and more frequent frosts developing, but temperatures have been a few degrees even lower than average this year.”
He said the colder nights followed an autumn that was “in transition” between the wetter La Niña months and the drier El Niño months to come.
“The combination of clear skies, light winds and cold air has caused minimum temperatures to be about three to five degrees below average in parts of Queensland and New South Wales this May,” Domensino said.
“It’s a combination of those developing climate drivers in the Pacific and Indian Oceans, but also the local weather patterns near Australia that have also played a big role in how cold it’s been.”
