The occasional late spring or even summer snowfall is far from rare in the Australian Alps, but the amount of snow coming this weekend could be pretty remarkable.

Around half a metre of snow should fall at higher elevations of the mountains in NSW and Victoria from Saturday night through to Monday, while snow will also fall in Tasmania.

Mainland snow levels should be quite low by Monday, with flakes falling as low as 900 meters above sea level on Sunday, and 800m on Monday, which means towns like Jindabyne on the fringe of the mountains could see snow too.

So why the unseasonal heavy snowfalls? 

The persistent rain event that has affected much of Australia this week has been caused by a low pressure system moving across the country from west to east. But once that low moves to the east of Australia, it'll drag cold southerly winds up over the Alps.

The southeast of the country will then be stuck with a cold south to southwesterly airstream for a few days, in a pattern which is more winter-like.

Normally at this time of year, southerly outbreaks don't have too much moisture associated with them, but the moisture lingering behind the low will ensure that there is plenty of potential for decent snowfalls in mountain districts down south.

When was the last heavy November snowfall? 

As mentioned, light November snowfalls are not too unusual, but anything more than about 10 centimetres after October tends to stick around in the memory of mountain locals.

A fall in November 2018 delivered up to 20 centimetres to Thredbo and nearby areas, while this was the scene on December 1, 2019, at Mt Hotham in Victoria.

Image: As you can see, there was a good 40 centimetres or more on the table on the first day of summer. Source: Author's pic. 

Meanwhile a heavy snowfall in early December 2013 delayed a major mountain bike festival in Thredbo by several days due to snow on the track.

Thredbo's mountain bike season officially opens on November 20 this year. They'll be glad they didn't kick things off a week earlier, as it looks like the tracks will be buried from Sunday for at least a couple of days.

As you'd expect with a cold outbreak like this, maximum temperatures in the southern capitals will be brisk, with Melbourne, Hobart, Canberra and even Adelaide all struggling to reach beyond the mid-teens from Saturday onwards for a few days.

Indeed the national capital should reach just 12°C on Monday. Its coldest November day on record was a max of 9.1°C in 1965.