Great weather divide across Australia taking hold

The final days of winter are shaping to bring massive contrasts in daytime temperatures across Australia of 40 degrees or more.

In parts of south-eastern states, the mercury will struggle to lift above zero, while in northern Australia, temperatures are forecast to hit 40 degrees, Weatherzone reports.

Tasmania, Victoria, South Australia, the ACT and south-western NSW are being blanketed by a frigid polar air mass that will send temperatures plunging from today.

READ MORE: A warmer and wetter spring in store for much of Australia, Bureau of Meteorology says

The highest alpine weather stations, such as Thredbo in NSW, are forecast to have maximum temperatures of -4 degrees through to Saturday.

Meanwhile, the Northern Territory's north-west and north-eastern WA are heading for their first 40-degree day as the late dry season takes hold.

If the mercury hits that mark, it would be at least five degrees above average for August in the Top End.

Weatherzone meteorologist Joel Pippard says the concentration of heat is down to last week's static weather pattern.https://twitter.com/BOM_NSW/status/1960808628102840377?ref_src=twsrc%5Etfw

"The most recent pattern of frequent cold fronts down south has helped to concentrate the heat into a line, create a sharp temperature contrast across the country," he said.

The initial blast of cold air swept through south-eastern Australia early today.

It followed heavy rain in alpine regions, with the Perisher Valley in the NSW Snowy Mountains receiving a 90mm downpour.

Sub-zero temperatures, powerful winds and snowfalls are expected there for the next three days.