Prime Minister Jacinda Ardern made the announcement at a briefing at 9pm last night saying that the alert level changes would come in from 6am today and would be in place for seven days.
She said Cabinet would assess the alert levels but it was likely that Auckland would remain in alert level 3 for the full seven days.
Ardern said the announcement comes after two new Covid-19 community cases that could not be directly linked to earlier cases.
One is the 21-year-old sibling of a student from Papatoetoe High School, despite the secondary school student showing no symptoms and testing negative three times.
The siblings' mother has also tested positive.
The 21-year-old was potentially infectious before testing positive and has not been self-isolating.
Genome sequencing is underway and Director General of Health Ashley Bloomfield, who also spoke at last night's briefing, said it was likely the transmission route was via Papatoetoe High School.
The 21-year-old has done airport work but is not believed to have any interactions with the airside or contact with potentially infected people, Bloomfield said.
The conditions of alert level 3 remain the same as last time.
Aucklanders are asked to stay at home in their bubbles other than for essential travel. If they do venture out, such as to essential retail stores, Aucklanders must maintain a 2m distance.
Children are asked to stay home from school in Auckland, although for essential worker parents who need to be at work, they will be open.
Supermarkets, pharmacies, petrol stations, and primary produce stories can remain open. Ardern urged people not to rush to supermarkets.
Businesses that normally operate on face-to-face basis are now asked to move to non-contact methods like click and collect or online ordering, she said.
Public venues will be closed, including playgrounds, libraries, cinemas, gyms, pools and markets.
Gatherings outside people's bubbles is prohibited with the exception of groups of 10 for wedding services, funerals and tangihanga. Public health measures will still need to be maintained in these events.
All sports games will need to be cancelled, including today's planned Auckland Round the Bays.
Travel into, out of or through the Auckland region is restricted while the region is at level 3. People who lived in Auckland but are currently away could return, and anyone who was in Auckland but did not live there could leave, Ardern said.
Those who are vulnerable with pre-existing conditions and older people are encouraged to stay at home where possible and take extra precautions where possible.
Aucklanders are asked to wear masks when they leave their house.
Level 2 for the rest of the country means business and schools remain open, but with social distancing.
People are asked to maintain a distance of 2m from others in public spaces and retail stores and in other places to stay 1m apart in places like workplaces, cafes, restaurants and gyms.
Masks are mandatory on public transport and encouraged where physical distancing is not possible.
Gatherings, including weddings and funerals, are limited to 100 people.