"Our family tradition since I've been prime minister is that I'll head to Australia," Ms Ardern told AAP.

"Usually we go to the Sunshine Coast but this time I'll be closer to Sydney."

The prime minister will spend Christmas and see in the New Year near Gisborne on the east coast of New Zealand, with extended family, including several nieces and nephews.

She'll then cross the Tasman for a more intimate break in early January in northern NSW.

The Labour leader said she still got to have "normal summers" in New Zealand since taking the country's top job, but the chance to be ever-so-slightly more anonymous in Australia was a drawcard.

"It's not to escape or anything like that because in Gisborne we have a wonderful time," she said.

"It's just we don't have to take our security. We can be by ourselves. It's really nice. We can be a bit more spontaneous."

Ms Ardern spent the last weeks of her working year dealing with the fatal White Island volcano eruption, nine months after 51 people were killed in the Christchurch mosque shooting.

She will face an election around September 2020, with recent polls indicating her Labour-NZ First coalition will narrowly lose power.

Her other big bit of business next year is planning her upcoming nuptials with Gayford; bluntly ruling out a fast-tracked ceremony in NSW.

"We won't be getting married in Australia," she says.

"Planning? Maybe if we manage to turn our minds to it. But that doesn't sound very relaxing to me."

Australian Associated Press