Parts of southeastern Australia could register their lowest temperature in a couple of years this weekend, with frost likely to extend from Tasmania up to Queensland.

A wintry air mass that originated over the Southern Ocean is spreading over southeastern Australia today in the wake of a cold front.

This frigid air is causing temperatures to plummet and it's going to get even colder during the next couple of days and nights, as another front reinforces the cold air mass.

Image: 850 hPa temperature from the ECMWF model, showing a cold air mass sitting over souteastern Australia on Saturday.

At 9:30am AEST on Friday, the temperature was sitting on 12.6ºC in Melbourne and 9.3ºC in Hobart. However, the effect of wind chill made it feel like 10ºC and 2ºC in each city, respectively.

Hobart is forecast to reach 12ºC on Friday and 11ºC on Saturday, with an overnight low of 5ºC in between. This is several degrees below average for this time of year.

In Melbourne, forecast 'highs' of 14ºC on Friday and 13ºC on Saturday would make this the city's coldest pair of days in seven months.

But while it's already feeling wintry across Australia's southeast today, the lowest temperatures will occur once the wind calms down and clouds clear.

By Saturday night and Sunday morning, temperatures will get low enough for widespread frost from Tasmania up into southern Queensland.

Canberra is forecast to drop to a bone-numbing minus 5ºC on Sunday morning. If it gets there, this will be the city's coldest May morning in six years and its lowest temperature for any month in almost two years.

Alpine weather stations such as Perisher Valley are forecast to hit minus 7ºC on Sunday morning. Further north, Glen Innes in northern NSW is tipped to get to minus 4ºC on Sunday and Monday mornings.

For Queensland, this cold snap could bring the state's first sub-zero temperature so far this year, with Stanthorpe forecast dip to -1ºC on Monday morning.