This week's prediction came as some international researchers predicted growing chances of a return to the normally wetter, cooler La Nina later in the year.
The Bureau of Meteorology last night predicted maximum temperatures across almost the entire country would likely be higher, while many parts were expected to experience daytime and overnight temperatures in the warmest 20 per cent ever recorded.
It said with the exception of parts of the Northern Territory and Queensland, there was at least a 50 per cent chance of "unusually high" winter maximums.
Minimums were expected to be just as much warmer than average outside of central and southern Australia.
But a BoM spokesperson said it was too early to confirm whether 2024 would be the warmest winter on record.
Weatherzone meteorologist Felix Levesque said it was hard to point to specific causes this far out but noted a La Nina shift could lead to more cloud cover in parts, trapping heat in overnight.
He also pointed out the impact climate change was having on pushing individual years outside long-term averages.
"The average does span quite some decades," he told 9news.com.au.
"That trend, due to climate change and the warming climate mostly, it becomes harder and harder to become below average over a period of time as the general climate warms up."
The Bureau said its averages were based on data from 1981 to 2018, which excludes many of the hottest years on record.
After a supposedly drier El Nino summer that saw big parts of the country repeatedly soaked, La Nina appeared more and more likely to return.
Weatherzone today pointed to new data from the US Climate Prediction Centre and Columbia University's International Research Institute for Climate and Society pointing to an 80 per cent chance by late winter or early spring and an 86 per cent chance by late spring or early summer.
But it noted the Australian model suggested neutral conditions through to late winter and early spring. Four of seven international models predict La Nina by late winter.
"A pool of unusually cold water has been growing over the last month in the eastern tropical Pacific Ocean, hinting that the foundations of a La Niña event may be lurking beneath the surface," Weatherzone said.
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"The large supply of abnormally cool water in the eastern tropical Pacific Ocean does add some weight to the possibility of La Niña returning this year. However, it is too early to know with much certainty whether this will happen or not."
The weather bureau earlier this month still had the ENSO outlook at El Nino but said the climate driver was nearing its end.
"Climate models indicate sea surface temperatures in the central tropical Pacific are expected to return to ENSO-neutral later in autumn 2024," BoM said today.
"Global sea surface temperatures have been the warmest on record for each month between April 2023 and March 2024. Notably, the Atlantic Ocean is showing exceptional and prolonged warmth in sea surface temperatures."
The Bureau said there was a 60 to 80 per cent chance of a drier-than-normal winter for northern Australia and small areas of southern Australia, with wetter weather likely for Gascoyne of WA, and scattered parts of eastern and central Australia.
Parts of northern WA, most of NT, and western Queensland were likely to face winters in the driest 20 per cent of all time.
The bureau's official winter long-range forecast is due in May.
