NSW has recorded its highest number of daily COVID cases since the latest outbreak began last month, with the health minister warning most infections are being diagnosed in people under 35.
There were 124 new locally acquired cases recorded to 8pm on Wednesday, with at least 70 active in the community for all or part of their infectious period.
Premier Gladys Berejiklian warned people to brace for cases numbers to rise further.
"We anticipate case numbers will continue to go up before they start coming down," she said on Thursday.
Health Minister Brad Hazzard stressed the highly contagious Delta strain was "a really serious issue for young people".
"Now what we've got is effectively almost a new virus in the sense that I think the current numbers are showing almost 60 per cent are young people under the age of 35," he said.
"We have young people in intensive care."
Of the 124 cases, 94 are from southwestern and western Sydney, while 18 are from the Sydney Local Health District.
There were eight cases recorded in southeastern Sydney, two in northern Sydney, and one case each in the Illawarra and the Blue Mountains.
The premier says the results of the harsher lockdowns won't be clear for several days.
"We haven't had the results of what the harsher lockdown restrictions may have had and that won't happen until early next week," she said.
"We need everybody to appreciate - I think people are quite shocked as to how different and contagious the Delta strain is."
The spike in cases was up from 110 the previous day, while the previous high was 112 cases announced on July 12.
Of the 124 cases, 37 were in isolation throughout their infectious period, 22 were in isolation for part of their infectious period and 48 cases were infectious in the community.
The isolation status of 17 cases remains under investigation.
NSW Health said there were currently 118 people in hospital with COVID and 28 in intensive care, with 14 ventilated.
Ms Berejiklian said the record 85,185 number of tests had resulted in higher case numbers.
NSW Health's Jeremy McAnulty said the new numbers included three workers in two Sydney aged care facilities.
A worker at a southern Sydney aged care home, The Palms at Kirrawee, has tested positive.
"This person wasn't vaccinated and the residents and staff have been tested. Two staff members at an aged care facility in Belrose have tested positive," Dr McAnulty said.
More than five million people in Greater Sydney and surrounding regions will have to wait until at least the weekend to see what impact harsher lockdown rules have had and whether the lockdown will end on time.
Ms Berejiklian says the virus must be quashed before restrictions, now in a fourth week, can be lifted but said she didn't want to "delve into the hypothetical".
"From July 31 we hope to be able to explain to the community what we can do in relation to adjusting those settings," she said.
The lockdown was meant to end on July 30.
She said many people were becoming infected while undertaking legitimate activities - "buying groceries, going to the pharmacist, having to undertake critical work".
People in the central-western local government areas of Orange, Blayney and Cabonne on Thursday entered day two of a week-long lockdown, after a COVID-19 positive delivery driver from Sydney infected a factory worker.
It's the first time stay-at-home orders have been imposed in regional NSW and thousands of people in those towns spent Wednesday in long queues waiting to be tested.
Since the outbreak began in June 16, 1648 people have contracted the virus.
Australian Associated Press