South-eastern Australia had its coolest winter for decades in some regions but seasonal temperatures for most of the country were above average and the mercury will soon start to climb, meteorologists said.
With winter officially ending on Monday, Sydney will have had its coldest winter by mean temperatures since 2010. For Melbourne, it was the most chilly since 1989, according to Weatherzone.
The Bureau of Meteorology said that final day figures could affect the comparisons for Sydney with the latest temperatures matching those of the 2012 winter. Maximums for the city are running at 0.8 degrees above the 1961-90 average and minimums 0.1 degrees below.
For Melbourne, the mean temperatures were just 0.1 degree below 1997's level so Monday's result "could conceivably push it level" with that year, making it only the coldest in eight years, Blair Trewin, senior climatologist with the bureau, said.
"The last couple of winters have been quite mild across south-eastern Australia, so this year was more typical of what we used to get," Ben McBurney, a meteorologist with Weatherzone, said. "It has certainly come as quite a shock for some."
Sydney, for instance, will come in about 1 degree above the long-term average for temperatures across the winter. Although the early mornings felt cold, only July among the three months of winter was below average for minimums - and only just, by about 0.1 degree, said Rob Sharpe, also a Weatherzone meteorologist.
Australia as a whole will post a warmer-than-average winter, particularly for the north and west, according to the Bureau of Meteorology. See chart below:
September will get off to a mostly sunny start in Sydney and Melbourne on Tuesday before rain arrives later in the week, particularly Thursday.
The low pressure trough, though, is unlikely to develop into an east coast low and will instead head "straight out to sea", Mr Sharpe said.
Conditions, though, should warm up early next week, particularly for Sydney where a string of days with tops of 22-23 degrees can be expected, he said.
"It will feel like we're getting into spring," he said.
Nationally, the most notable warmth was in WA and Queensland, Dr Trewin said. Below-normal temperatures were largely confined to the south-east regions of the country, particularly for Victoria, Tasmania, southern NSW and southern SA.
"NSW hasn't had a below-average winter for mean temperatures since 1997, a record which will not be spoilt in 2015," Dr Trewin said.
Spring outlook
The bureau last week released its three-month weather outlook for the country, predicting a wetter-than-average spring for central and western parts of the country and more average conditions for the rest.
The additional cloud expected will likely mean day-time temperatures will be mild for spring, the bureau said:
The odds, though, strongly favour milder than average overnight temperatures during the September-November period, according to the bureau:
Rainfall and climate influences
Rainfall during the winter months was on the low side for both Sydney and Melbourne.
Sydney received about 229 millimetres of rain over the June-August period, or about 74 per cent of its long-run average, Weatherzone said.
Melbourne's 124 millimetres was about 84 per cent of its usual for winter.
The sub-par rain came as a strong El Nino event developed in the Pacific. Such events tend to see rainfall shift away from Australia as easterly trade winds stall or reverse.
The winter, though, would have been drier across much of southern Australia if not for the countering influence of exceptionally warm waters in the Indian Ocean. (See chart of temperature anomalies below:)
"Generally speaking, [the Indian Ocean warmth] is going to moderate the effects of the El Nino, particularly during the late winter and into spring," Mr Sharpe said.
The record El Nino year of 1997-98 was characterised by close to average rainfall across much of Australia in large part because of moisture still reaching much of the country because of favourable Indian Ocean conditions leading to more convection.
"It looks like [the El Nino] might not be all that bad for Australia," Mr Sharpe said, adding that its impacts globally may still be large.
