Temperatures have plummeted to below-average across Australia, with the freezing conditions set to continue.

Canberra shivered through minus 5.6 degrees just before 6am on Tuesday, with drivers warned to take extreme care because of icy conditions on the road.

It was 1.3 degrees in Sydney’s Penrith, 1.8 in the Melbourne suburb of Viewbank, and -3.9 at the Oakley defence site in Brisbane.

The mercury plummeted to -3.8 degrees at Grove, south-west of Hobart, and 2.7 at Nuriootpa, north of Adelaide.

It was 1.8 in Sydney on Monday, making it the coldest June morning on record.

However, that particular weather monitoring site was established only 12 years ago.

The Bureau of Meteorology received anecdotal reports of 15-30 centimetres of snow in alpine areas, senior meteorologist Miriam Bradbury said.

Temperatures plunged below zero in southern Queensland, with Oakey falling to -3.7 degrees.

Elsewhere on the Darling Downs, Dalby reached -2.5 degrees and Goondiwindi shivered at -0.9.

Brisbane’s minimum was below 10 degrees and the airport recorded 8.1.

Queensland’s south-east was expected to post below-average temperatures under mostly clear skies for the rest of the week.

Cold air from the Southern Ocean is being blown across south-eastern Australia, with a high-pressure system reinforcing the chilly conditions.

Ms Bradbury said temperatures were again tipped to dip below zero in parts of south-east Queensland, Tasmania and inland NSW and Victoria overnight.

The chill is likely to continue until the end of the week but temperatures are forecast to rise above average in some areas at the weekend.

Sheep graziers across regional NSW have been put on alert, with a warning sheep and lambs exposed to the tough conditions are at risk.

– AAP