Victorian Premier Daniel Andrews has outlined a four-step plan for the state to return to normality, with some restrictions to be tweaked from midnight next Sunday.

But Melbourne will remain under a nightly curfew and people will be unable to leave their homes for non-essential reasons until at least October 26.

The lockdown will lift on that date if the average number of new cases falls below five and there are fewer than five unknown source cases.

Up to five visitors from a nominated household and outdoor gatherings of up to 10 people will also be allowed.

"We can't run out of lockdown. We have to take steady and safe steps out of lockdown to find that COVID normal," Mr Andrews said on Sunday.

"I want a Christmas that is as close to normal as possible and this is the only way, these steps are the only way that we will get to that point."

The premier said the nominated 14-day average of five cases provided a 97 per cent chance of avoiding having to go back into lockdown.

Victoria's average daily number of cases during the previous 14 days was about 100.

"If you open up at that level you are not open for long," he said.

"We either do it this way or in fact, we won't be opening up at all. We'll just have a short respite from these rules, which I know and appreciate and understand are incredibly difficult."

The last step will come into effect from November 23, if Victoria goes 14 days with no new cases, allowing public gatherings of up to 50 people and 20 home visitors at a time.

All remaining restrictions will be removed when Victoria goes 28 days with no new cases, although masks will likely remain compulsory for some time.

The premier conceded the long road ahead would be incredibly challenging for Victorians, and mental health support organisation Beyond Blue issued a statement reminding those affected that free support was available to everyone.

"If you're struggling to cope, pick up the phone or go online - don't wait until things get worse or you reach crisis point," the statement said.

Melburnians will at least soon take back some freedoms. From September 14, the nightly curfew will start an hour later at 9pm and run until 5am.

People living alone can nominate a friend or family member who can visit them and two hours of daily exercise will be allowed, including "social interactions" such as having a picnic at a local park or reading a book at the beach.

From September 28, up to five people from a maximum of two households can meet outdoors for social interaction.

Childcare centres will be allowed to reopen without permits and workers across construction and manufacturing can return to their jobs, along with landscape and maintenance workers who operate alone.

All VCE and VCAL students across Melbourne and regional Victoria will sit the General Achievement Test in person from October 5.

From October 12, Melbourne's prep to year 2 students, VCE and VCAL students and those attending specialist schools will return to face-to-face learning. All regional students will return in the same week.

The move to "second step" restrictions from September 28 will happen only if there is an average daily case rate of 30 to 50 cases in metropolitan Melbourne over the previous 14 days.

The state's opposition and business groups have criticised the plan, which they say could lead to the closure of countless companies.

"Until we have a vaccine, until we have a cure, we need to be able to live with this virus and that means finding ways to safely reopen," Opposition Leader Michael O'Brien said.

On Sunday, Victoria recorded 63 new cases and five more deaths, taking the state's toll to 666 and the national figure to 753.

Australian Associated Press