Premier Gladys Berejiklian said NSW recorded 18 cases of community transmission to 8pm on Sunday night, praising the community for seeking testing and obeying the rules.
NSW chief health officer Dr Kerry Chant said there would likely be a "much lower threshold" for classifying people as close contacts after children who had attended some Sydney schools were among the latest to test positive.
All but one of the latest cases has been confirmed as a link, Ms Berejiklian said, and the final case was "in the vicinity" of the others.
"About a third of them, about six of them, were in isolation for the entire time," she said.
Others were isolated for part of their infectious period but "some unfortunately were active in the community."
Dr Chant said 15 cases were linked to the Bondi cluster and the other three were acquired overseas.
The state conducted 58,870 tests in the 24-hour reporting period.
Ms Berejiklian also called on people to remember that there was a lag in the figures, so they would not reflect the lockdown measures introduced on Saturday in the next few days.
"We have to be prepared for the numbers to bounce around, and we also have to be prepared for the numbers to go up significantly." she said. "We are seeing a really high rate of transmissability."
The state broke its vaccination record last week, with 105,000 people inoculated.
Questioned why regional NSW had been placed under more stringent precautions, Ms Berejiklian said there was "no reason" the regional restrictions should last more than a fortnight if people adhered to the rules.
She said the decision would ultimately depend upon public health advice.
"Even if you haven't had a case in your community, the restrictions are there to ensure that will continue," Ms Berejiklian said.
"The risk is there even though the cases aren't there so I think it's only appropriate to have those restrictons in place."
The Premier also urged people to keep their focus on NSW Health and press conference updates, and to ensure their sources of information were reputable and reliable.
"The most important message I'd like to give everybody is we have to assume that ourselves and others around us have the virus," she said.
Dr Chant said rather than numbers in coming days, she urged people to focus on whether those cases were in isolation and if they were linked to known infections.
"We will need another five days to see this situation turn around," Dr Chant said.
"The cases we have now reflect exposures that occurred five days ago, therefore it is important the community understands the numbers are not expected to decline for another five days.
"We all have a role in adhering to public health advice."