Prime Minister Scott Morrison has again praised the resilience of Australians in facing up to the COVID-19 pandemic.

Australia is heading into the final weeks of the year with an ever-improving report card in tackling COVID-19, especially for its two most populuous states.

NSW has recorded its 22nd consecutive day without a locally-acquired case of COVID-19, inching closer to the benchmark 28-day for virus elimination.

The once COVID-ravaged state of Victoria has now clocked up 30 days without a new case.

Prime Minister Scott Morrison believes Australia's secret in tackling the pandemic has been its people's resilience.

"We've done, especially in COVID, better than almost any other country in the world," Mr Morrison told ABC radio on Sunday.

"I said at the start of the COVID pandemic that we know we're a strong people."

However South Australian and Western Australia have suffered setbacks after both states reported quarantine breaches on Sunday.

While the WA incident involved a man who was supposed to be in self-isolation being nabbed at a local pub, the SA breach was more serious.

Authorities first had to issue an alert asking people to self-quarantine if they visited the Intensive English Language Institute at Flinders University between November 13 and 28.

Then they had to set up two testing clinics after they found a man had breached quarantine and visited seven different shops in seven locations across Adelaide.

Chief Health Officer Nicola Spurrier says she's disappointed in the man's actions and called on people to comply with health directions.

"You have to do the full 14 days of quarantine," she said.

On Saturday, Mr Morrison told NSW party faithful he was optimistic 2021 would be better than 2020, as the government prepares to roll out a vaccine in the first quarter of next year.

He said Australia had heavily invested in four vaccines - Novavax, Pfizer, AstraZeneca and a University of Queensland vaccine - which he said should be introduced in the first three months of 2021.

The prime minster remains in isolation in The Lodge following his recent official visit to Japan.

He will dial into parliament on Monday for the start of the final sittng fortnight of the year.

But as the temperature gauge rose this weekend, Australians were again being told not to be complacent.

Parts of Sydney broke the 40C barrier on Saturday while swathes of western NSW, South Australia and northern Victoria baked through even higher temperatures approaching 45C.

NSW Health's Michael Douglas said the state's residents should continue to be on alert for undetected virus transmission.

"Everyone is encouraged to continue to come forward for testing with even the mildest of symptoms that could signal COVID-19," he said.