Nearly five million residents of greater Melbourne and the Mitchell Shire are set to enter a very different world from midnight Wednesday, with a new six-week lockdown coming into effect.

On Tuesday Premier Daniel Andrews reinstated stay at home restrictions across metropolitan Melbourne and Mitchell Shire, to the north of the city, to take effect from 11.59pm on July 8.

He announced 191 new cases of Covid-19 on Tuesday including 154 under investigation.

None of the cases were detected in returned travellers in hotel quarantine in a worrying development showing the virus is established in the community.

There are 772 active coronavirus cases in Victoria and 35 people are in hospital. Nine of those patients are in intensive care.

THE AREAS AFFECTED

The restricted areas are Mitchell Shire and 31 local government areas across the greater city: Banyule, Bayside, Boroondara, Brimbank, Cardinia, Casey, Darebin, Frankston, Glen Eira, Greater Dandenong, Hobsons Bay, Hume, Kingston, Knox, Manningham, Maribyrnong, Maroondah, Melbourne, Melton, Mitchell Shire, Monash, Moonee Valley, Moreland, Mornington Peninsula, Nillumbik, Port Phillip, Stonnington, Whitehorse, Whittlesea, Wyndham, Yarra and the Yarra Ranges.

"2020 has not been the year any of us wanted," Andrews said when announcing the news.

"Cancelled events. Plans put on pause. Uncertainty about what the future holds.

"And I guess that's why so many people want to pretend this is over."

He stressed the stay at home direction applies to principal places of residence.

"That means no escaping to holiday homes," Andrews said.

According to a summary of the restrictions, second places of residence outside restricted areas cannot be visited except for limited exceptions such as an emergency or maintenance, shared custody, or to stay with an intimate partner who does not live with you.

The state's chief health officer Professor Brett Sutton said Victorians have got "six very difficult weeks ahead".

The new directions are to continue until 11.59pm on August 19.

No one in the impacted areas is allowed to have private gatherings with visitors, and public gatherings are limited to "two people or household members only".

"For people who live in regional Victoria, where case numbers remain low, current restrictions will remain the same for now," Andrews said.

Regional Victorians cannot enter restricted areas except for "necessary purposes" being necessary goods or services, work and education if necessary, medical care or compassionate reasons.