"We want to be very clear... that September and October will be difficult for NSW," the premier said on Thursday.
The state again broke its record for case numbers, with 681 people testing positive in the 24 hours to 8pm on Wednesday.
A man in his 80s became the latest death of the outbreak which started in mid-June.
But there is a "light at the end of tunnel" as vaccination numbers continue to rise, the premier said.
The government is currently looking at ways to give vaccinated people more freedom in September when the state has reached six million jabs.
But Ms Berejiklian refused to elaborate on what exactly that would look like.
Most of Thursday's cases were again in western Sydney and southwest Sydney.
Deputy Chief Health Officer Marianne Gale said the "vast majority" of positive cases were doing the right thing.
"What we are seeing is that transmission occurs so easily in households and... those people that provide essential services, who worked in aged care, work in disability, who work in healthcare settings, who work in factors, work in shopping centres," she said
"And so, transmission is happening between workplaces and households."
But the union representing manufacturing workers says health authorities have failed to listen to its concerns.
AMWU NSW & ACT Branch Acting state Secretary Robyn Fortescue said workers were telling the union that employers are cutting corners when it comes preventing and responding to infections.
NSW Health is allowing the employer to identify and contact close contacts, she said.
"There is no consultation whatsoever happening with the affected workers, who are best-placed to identify the risks and transmission chains on the ground," she said.
The AMWU wants the government to involve workers in the response to workplace infections, bring unions on board to a committee to address workplace infection risks, and set up a hotline where workers can call NSW Health if their employer is doing the wrong thing.
The state broke another record for daily vaccinations on Thursday, with 132,439 people reported to have received the jab.
Some 55.2 per cent of people over 16 have now had at least one dose of the vaccine.
The entire state is now in lockdown until at least August 28, after the government extended restrictions in regional NSW by another week.
Related Stories
Comments
The Berejiklian Government is trying to impose the British system of just letting people die for the sake of business, on the whole of Australia. It is frightening being in NSW and seeing Gladys pretending to act, while ensuring that she never does enough to succeed. Our only hope is for NZ to show up her incompetence by beating the current outbreak, and for the other states to isolate NSW and to keep themselves safe. There are nowhere near enough vaccine doses in Australia for everyone, but all the politicians made sure they and their families got their shots.
We are at the mercy of heartless, corrupt politicians who think about nothing but themselves and the people who donate to them. NZ is so lucky.