Other cutbacks of an hour or half-hour are minimal and several libraries will be open for longer.
Council must cut its cloth, mayor says, as core service shrinks.
Most libraries will have reduced opening hours, while some others will be extended, in a bid to save $1.1 million in Auckland Council's proposed budget.
The core service is not spared in the 10-year budget, which also targets a 7 per cent cutback in park maintenance. The city's 55 libraries will remain open on Saturdays, but Whangaparaoa, Mahurangi East and Birkenhead or Northcote will be closed on Sundays.
Warkworth, Ranui and Otahuhu will, however, extend their opening hours to include Sundays.
The Botany library has the biggest reduction, losing 12 hours to end up with 56, followed by Waitakere library and research centre, which loses 10 hours.
Even the hours at the central city library are being cut by five, doors opening on weekdays at 10am instead of 9am.
Other cutbacks of an hour or half-hour are minimal and several libraries will be open for longer. Warkworth will gain an extra six hours and Wellsford an extra three.
For libraries open Monday to Saturday, it is planned for a "neighbouring" library to be open on a Sunday to keep a seven-day service within reasonable reach of the community.
"Auckland will have more libraries open on Saturdays and Sundays than we do now, which is when many people want to use them," a spokeswoman said. "The proposed changes ensure a fair and standardised approach to library hours across the region and allow us to save costs, helping keep rates as low as possible."
In the past year, four new library buildings have opened, at Waiheke, Ranui, Te Atatu Peninsula and Devonport, which will lose three and a half hours of service at its new $7.8 million library.
The council also plans to introduce a $1 fine for people who don't pick up a requested book.
Mayor Len Brown said the council was looking for savings in every single budget. The message from the community was to "cut your cloth".
"At the same time as delivering greater libraries open during the weekend and availability for the whole of the community we're also getting savings. That sounds like a reasonable sort of deal," he said.
But one source told the Herald the reduced hours were being pushed through under the radar and some library staff were being forced to change their hours.
In 2012, a plan to close the Mahurangi East and Grey Lynn libraries to reduce rates was abandoned after 600 people signed a petition against the Mahurangi East proposal.
Closing Brikenhead branch on Sundays no laughing matter
Yesterday, 5-year-old Noah Phillips took out his first book of jokes from the Birkenhead library. He's just started school, and loves a laugh, cracking up after his dad Dov reads him an old favourite: "What kind of coat is put on wet?" "A coat of paint."
Closing the library on Sundays, as is proposed by the Auckland Council, might deprive Noah of the chance to become a comedian, Mr Phillips says.
He's partly joking, too - but believes the site should stay open on both weekend days.
"You've got to encourage more people to read," he says. "And it's brand new - why should it close?"
Under the proposal, either Northcote or Birkenhead library would shut on Sundays, meaning residents would still have the opportunity to go to one nearby, the council says.
Mr Phillips, who visits the library twice a month with his son, said they should both stay open.
Another pair of library-goers, Meredith Schollum and her daughter Toni, 15 - who were returning French picture books Toni used to help with her language lessons - also wanted to be able to visit on Sundays.
Toni said they visited every second week, as she is usually busy after school and can't make it in time for 5pm closing.
Jane Arrowsmith, a primary school teacher, said a lot of people couldn't make it during the week.
The 10-year budget. What's it all about?
According to Mayor Len Brown, the 10-year budget includes some of the biggest decisions on Auckland's future.
For households, it means big rates increases - an average of 5.6 per cent this year and 4.5 per cent a year thereafter.
Other factors see rates see-sawing from decreases of 20.5 per cent on Great Barrier Island to more than 40 per cent for 3738 unlucky households.
The budget determines how Auckland tackles transport over the next decade.
Does the city stutter along in the slow lane, spending less and getting less, or pay a motorway toll of $2, or a petrol tax and higher rates for a better transport programme?
Whatever pans out, funding is locked in for the $2.5 billion City Rail Link, which the council says will revolutionise travel and fundamentally change the growth and infrastructure landscape of the city.
The budget is out for public consultation and submissions close on March 16. It will then go to councillors for approval, before coming into effect on July 1.