Spring is a season of contrasts, and sometimes those dramatic weather differences occur on the same day in the same state.

That will be the case this Saturday in New South Wales, when parts of the state's northwest will see temperatures pushing up into the mid-30s, while snowfalls develop later in the day in the Snowy Mountains in the state's south.

The current BoM forecast for Brewarrina, a small town of around 700 people about 800 kilometres NW of Sydney, is for a Saturday maximum of 35°C.

Down south at Thredbo Top Station (Australia's highest weather station at 1957 m), snowfalls should commence on Saturday afternoon, lowering to mid-mountain at around 1600 m, and perhaps even falling as low as Thredbo village (1370 m) overnight.

Why the stark contrast between hot and cold?

It's been at least three weeks since the last significant cold airmass pushed northwards over the southern Australian mainland. This has allowed unseasonable warmth to build up over inland regions.

A high pressure system currently centred over eastern Australia will move out over the Tasman and Coral seas on Saturday.

Air naturally moves from areas of high pressure to low pressure, and as the low pressure system and associated cold front cross the southeastern mainland on Saturday, northwesterly winds will strengthen as air circulates anti-clockwise around the high, dragging warm air across New South Wales.

A very warm afternoon is likely across the whole northern part of NSW and much of the east – even as much cooler air pushes into southern parts of the state.

Sydney still set for first 30-degree day of the season

Weatherzone meteorologist Ben Domensino wrote on Wednesday that Sydney was likely to hit 30°C on Saturday, and that's very much still the likely scenario.

The latest forecast suggests the mercury could push as high as 31°C in the city and 32°C in some outer western suburbs like Penrith and Richmond. 

In contrast, Melbourne is not expected to break 20°C on Saturday with a string of much cooler maximums in the mid-teens expected after the passage of the cold front.

Sydney will also be cooler next week with maximums back around 20°C for at least a few days.

Will the coming snow save the ski season?

Unfortunately not. Firstly, large snowfall totals are not expected.

Image: An August view of the Ramshead Range near Thredbo from a mostly snowless valley which would normally be at least partially snow-covered in an average winter. Source: Weatherzone.

Secondly, there is now too much exposed rock and grass at all Australian ski resorts for any fresh snowfalls to make much of a difference for more than a day or so.

September snowfalls are meaningful when there's a decent remnant snowpack from winter onto which the new snow can bond. But as detailed in our story on Thursday, the Australian snowpack is at a historic low for the first week of September, even at the highest elevations of the mountains. 

Having said that, Sunday should be a decent day for any weekend visitors to throw a snowball, and conditions should at least be somewhat improved on ski slopes that are still open.

Please check the Weatherzone snow page for the latest forecasts, live cams and more.