It was the calm before the warm.

On New Year's Eve at holiday resorts the length of the country - where in past years drunken teenagers have fought and vomited, rioted and clashed with police - nothing much happened.

Then yesterday, New Year's Day, the sun settled in for the week, with a promise of hot, dry days to come.

Sure, there was the odd arrest on New Year's Eve - that's par for the course when the population of a small Coromandel town like Whangamata swells from 4000 to 40,000-plus overnight.

Senior Sergeant Peter van de Wetering said there were a few liquor ban breaches, and a couple of assaults in the town.

"We're concerned with the number of young people let on the loose without supervision," he said. "But the behaviour in general was noticeably an improvement on other years."

Christchurch police arrested 69 people - but that paled in comparison to the 12,000 who filled an earthquake-battered Cathedral Square to enjoy the fireworks and pray for a better year in 2011. In Nelson there were 21 arrests; in Wellington there were 20, and in Napier there were 18.

There was the odd injury, too. Take Mt Maunganui, for instance, where a St John Ambulance officer said they had given out two Panadol and strapped a young man's bent finger - but all in all things had been "a bit boring".

At Waikato Hospital, emergency department clinical director Dr John Bonning said surgeons had dealt with six broken jaws - the outcome of booze-fuelled fisticuffs.

But for the 99.9 per cent who avoided arrest or injury, New Year's Day dawned clear and warm.

And with the exception of north Otago where heavy rain and rising rivers are expected this morning, New Zealand can expect calm, warm weather all week. head analyst Philip Duncan says that is thanks to a high coming in from the Tasman.

"It's looking dry from top to bottom - traditional settled weather for this time of year."

Waikato, Taranaki, Manawatu and Wanganui are expected to be hotspots, with temperatures reaching the mid to late 20s, says Duncan. In Auckland, temperatures are likely to hover around 24C or 25C, with increased humidity.

Sea temperatures have also been hotting up, says Duncan.

Northland, where the sea was 20C to 22C, was the warmest followed by Auckland (20C), the Bay of Plenty (19C), and Hawke's Bay (17C).

The "people's prime minister", former broadcaster Paul Henry, was snapped in the surf near his Hawke's Bay holiday home this week.

As for the elected prime minister, John Key - well, he and his family were enjoying even warmer water temperatures on the beach outside their holiday home in Hawaii.

- additional reporters: James Ihaka, Andre Hueber, Leigh van der Stoep