Most of NSW is locked down and police are cracking down on compliance measures as authorities battle to contain the spread of the virulent Delta strain.

Of the four deaths in the 24 hours to 8pm on Sunday, two were men in their 60s and two people were in their 80s.

It takes the toll for the current NSW outbreak to 245, and the toll for the entirety of the pandemic to 301.

There are 1207 COVID-19 patients in hospital in NSW, with 236 in intensive care units and 123 on ventilators.

"Even if case numbers go down, we should expect unfortunately that the number of people in intensive care and the number of people who lose their lives to go up," Premier Gladys Berejiklian told reporters.

"As we've said consistently, because we have had a number of cases in the last few weeks, people ordinarily get very sick in the second week of the illness."

It comes as those in Sydney's hardest hit suburbs enjoy their first taste of freedom in months, with recreation rules relaxing as vaccination rates continue to climb.

Fully vaccinated adults in the 12 western Sydney local government areas will from Monday be able to exercise outdoors with no time limits, and gather in groups of five for outdoor recreation within five kilometres from home.

Children under 12 are not included in the gathering limit.

Conditions for authorised workers and travel permit requirements will remain in place in the LGAs of concern, however.

Public pools can reopen in NSW from September 27.

Monday is also the deadline for authorised workers to have been inoculated with at least one COVID-19 vaccine dose to be permitted to leave their LGA for work, unless they have a medical exemption.

NSW reported 13 deaths on Sunday - an outbreak record.

Australian Associated Press