Some schools are reopening for 2018 with unfilled teacher vacancies and principals are worried the teacher shortage will get worse as the year goes on.
The Secondary Principals' Association and the Auckland Primary Principals' Association said too few people were training to be teachers, and higher pay and better workloads would help to fix the problem.
Principal of Randwick Park School in Manurewa, Karen McMurray, said she started the year with three vacancies, but had managed to fill one by appointing a first-year teacher from the South Island.
"We're using a recruitment agency and they are sending through people they think are appropriate," she said.
"Yesterday we interviewed one person who was not appropriate and I have been advertising in the South Island newspapers since the third of January, twice weekly since then, and I have had one applicant and I have appointed that applicant," she said.
Ms McMurray said she hoped to hire suitable overseas teachers by the end of April, but until then two managers would have to fill the gap and that meant their management work would have to be spread among other staff.
Schools in other parts of the country were also struggling to appoint teachers.
Taihape Area School principal Richard McMillan said he had three vacancies and he was not optimistic about filling them.
"We need a new teacher of social sciences who can teach level three geography, we need a new science teacher who can teach right across the sciences - which is a big ask but we need someone who can teach NCEA level one to three - and we also need teachers who can teach year 9 and 10 subjects."
Mr McMillan said he had people covering the vacancies temporarily, but he had never found recruitment so difficult in the seven years he had led Taihape Area School.
Secondary Principals' Association president Mike Williams said the problem was probably going to get worse.
"The reality is the number of people going into initial teacher education has been dropping year after year," he said.
Mr Williams said assuming there was no change in that trend, the outlook was not good.
"Come the end of 2018 the situation is going to be even worse."
Education Minister Chris Hipkins said only a few Auckland schools were having serious difficulties hiring teachers and the Education Ministry was working directly with them.
"We've been training fewer teachers in recent years while the population has been increasing and a very large cohort of teachers, the baby boomer teachers, are nearing retirement," he said.
"So all three of those things have converged to create what I think is going to be an even greater problem in coming years to what it is now, so we've got a lot of work to do, to do a very rapid catch-up."
Mr Hipkins said the government was looking for new ways to train teachers and had waived the $4000 fee for the "refresh" course that many teachers returning to the workforce must complete.
He said more people needed to enrol in teacher education courses and the government would consider expanding the Teach First programme that trained teachers while they were working in classrooms.
Auckland Primary Principals' Association president Kevin Bush said the government needed to pay teachers more.
"What's needed is we have to make teaching attractive again," he said.
"It is a fantastic job. I've been in it for decades now and I love it every day, but we're just not getting people in there and the reason sadly that we're not getting people in there is they're just not seeing it as a career that pays enough."
Mr Bush said 2018 would be a watershed for teacher supply problems and the crunch would come in winter when schools found there were no relievers to cover for sick teachers because the relievers had been hired for full-time teaching jobs.