NSW has recorded 77 new community Covid-19 cases and one death due to the virus - and Premier Gladys Berejiklian has warned the numbers are only going to get worse.

Of the new locally acquired infections, 55 are linked to a known case or cluster – 39 are household contacts and 16 are close contacts – and the source of infection for 22 cases remains under investigation.

At a press conference this afternoon, Berejiklian said the person who died - a woman in her 90s - acquired the virus through a household contact.

"Tragically we've seen one older person die and I want to extend my deepest condolences to their families and loved ones and [NSW chief health officer] Dr [Kerry] Chant will provide further details," she said.

"Regrettably, that person did acquire it within the household, within the home setting."

She added that she expected tomorrow's numbers to be even worse.

"I'll be shocked if it's less than 100 this time tomorrow, of additional new cases," Berejiklian said. "So we can't stress enough the importance of not only following the rules but also realising the risk that the people who will suffer the most."

The Premier urged everyone in Sydney to assume they had the virus and act accordingly to stem the spread of the state's Delta strain outbreak.

There have been 566 community cases reported since June 16, 2021, when the first case in the Bondi cluster was reported.

The state yesterday recorded 50 new locally acquired cases. Of those 50 cases, 26 were infectious in the community prior to their diagnosis.