Christmas plans for people wanting to travel to and from NSW have been thrown into chaos with most states closing their borders to greater Sydney.

Western Australia and Queensland have also implemented hard borders with the state.

The COVID-19 cluster on Sydney's northern beaches grew to 83 on Monday after another 15 new cases of community transmission were identified.

But the NSW government was buoyed by that figure because new cases were half the 30 reported on Sunday, after a record 38,578 tests were conducted.

Health authorities say the next 48 hours will be critical after the NSW government locked down the northern beaches until midnight on Wednesday and resurrected a small set of restrictions for greater Sydney.

The prime minister said he understands how disappointing and frustrating the situation is, but is optimistic about the state's handling of the outbreak and the public's compliance with health directives.

"There is good cause ... to have hope that if they continue to apply themselves in the way they are, and the (public) cooperation continues, then we can hopefully see things returned to COVID-normal," he told reporters.

Mr Morrison didn't criticise the border closures, saying it was up to the states and territories to make decisions about public health.

He said the federal government has tried to ensure a consistent national approach through a hotspot regime, but states want to retain flexibility.

"What we need to look at is what the result has been, and that is Australia's had one of the most successful outcomes in suppressing the virus in this country of almost any other country in the world," Mr Morrison said.

NSW Premier Gladys Berejiklian made a last-ditch bid on Monday to get her state and territory counterparts to consider the "heartbreak" of tighter border restrictions at Christmas.

Residents of greater Sydney have been locked out of most jurisdictions across the country because of the Avalon cluster.

"All I'm saying to colleagues around the country is please think about the heartbreak," Ms Berejiklian said.

"It impacts not just people in NSW, but people in your home states that may not have been reunited with family or friends or significant others for a long period of time."

But her appeal did not deter her Queensland counterpart Annastacia Palaszczuk from announcing on Monday afternoon a hard land border will be reimposed from 6am on Tuesday.

Ms Palaszczuk said there was no other option after police caught almost 200 Sydneysiders in 24 hours trying to enter her state illegally.

"People will start to seeing barricades going up again this afternoon and it will be back to the strong border measures that we have seen in Queensland that have kept Queenslanders safe," she told reporters on Monday.

WA imposes a hard border with all of NSW on Saturday, while most other states banned people from greater Sydney and the Central Coast from Monday.

If they do travel, they will have to undergo 14 days' hotel quarantine in most states, or quarantine at home in South Australia and the ACT.

Only people from greater Sydney will have to quarantine for two weeks on arrival in Tasmania.

Greater Sydney stretches from the Hawkesbury, Hornsby and the northern beaches regions in the north, to the Blue Mountains in the west, and the Wollondilly, Campbelltown and Sutherland regions in the south.

Travellers from the Wollongong local government area also cannot enter SA, while the Northern Territory, ACT, and Queensland have barred the entire Illawarra/Shoalhaven region.

There is a 24-hour grace period for Queensland and Victoria residents returning home, with authorities allowing them to quarantine inside their own houses.

Australian Associated Press