NSW Health said on Sunday that a confirmed case had visited the McDonald's in William Bailey Street, Raymond Terrace, between 11.45am and 12.15pm on Tuesday, December 15.

Anyone who was at the restaurant between those times is regarded as a casual contact and should get tested immediately and isolate until they receive the results.

The University of Newcastle drive-in testing station reached capacity late Sunday morning as cars backed up to the inner-city bypass roundabout on University Drive.

Port Stephens MP Kate Washington said she had asked the government to set up a pop-up testing station in Raymond Terrace.

The town's existing clinic at Raymond Terrace Community Health Centre opened for four hours on Sunday to cope with demand.

The Pacific Highway was busy with holiday traffic over the weekend as the Queensland border remained open and Sydney, outside the Northern Beaches, was not yet in hard lockdown.

"There's lots of people travelling around and it's that time of year," Port Stephens mayor Ryan Palmer said.

"We're on high alert. The rumours that fly around don't help to ease any nerves.

"People need to be very aware that they're listening to NSW Health around what they should and shouldn't be doing and where people have and haven't been."

Mr Palmer said the timing of the Sydney outbreak was "terrible".

"I feel for everyone because everyone has been on high alert for such a long time and we were hoping for such a good Christmas and new year and a break away from the realities of 2020."

Victoria, Queensland and South Australia have closed their borders to Sydney and Central Coast residents, but the Hunter escaped the net.

Travel uncertainty has cast a shadow over the Hunter tourism industry before one of its busiest periods, but it remains unclear how the latest outbreak will affect visitor numbers.

The Port Stephens and vineyards tourism associations said on Sunday that they had not seen widespread cancellations yet.

But Mr Palmer said Port Stephens Council's holiday parks had received "a whole heap of cancellations".

"This is the time that [businesses] boost their coffers for the year, but, if we can't have people travelling at this time, we know people will be back," he said.

Premier Gladys Berejiklian said on Sunday that anyone from the Northern Beaches already on holiday in regional NSW should stay where they are and go out only for essential activity.

The greater Sydney area, including the Central Coast and Wollongong but not Newcastle, has reverted to the 10-person limit on visitors to a home until midnight Wednesday.

Pubs, clubs, restaurants and other indoor venues in greater Sydney have returned to the four-square-metre rule instead of one person every two square metres, and dancing is banned.

Ms Berejiklian encouraged people across the state to wear a mask when they are in an enclosed area such as supermarkets, shopping centres and places of worship.

She also urged people not to visit aged-care centres until Thursday.

The Avalon cluster grew by another 30 cases on Sunday.

Two of the cases contracted the virus from an unknown source, but both live on the Northern Beaches.

"Even though numbers are higher than yesterday, the one positive is we still have not seen evidence of massive seeding outside the Northern Beaches community," Ms Berejiklian said.

Northern Beaches residents are in lockdown until Wednesday night, but Ms Berejiklian stopped short of ordering the rest of Sydney to stay home.

"Can I say to everybody in other parts of Sydney ... please limit your activity. We're asking you to do this on good faith. We're asking you not to undertake non-essential travel," she said.

"To put everybody on notice, we will be considering today ... whether this time tomorrow we do revert back to some restrictions in greater Sydney."

She was hoping the restrictions until midnight Wednesday would allow the state to get on top of the virus then "ease up for Christmas and the new year".

NSW Health also issued an alert in Forster, where anyone who attended Café Toscano in Wallis Street for more than an hour on Wednesday, December 16, between 6 and 7.45pm is considered a close contact of a confirmed case and should get tested immediately and self-isolate until December 30.

A matching alert was also issued for Beach Bums Café, on the corner of Beach and North streets, for Wednesday December 16 between 8am and 9am, and Thursday December 17, 8am and 9am.

Other people who attended the cafe for less than an hour during this time should monitor for symptoms and get tested immediately if they appear.

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