Waikato journey manager Liam Ryan said: "Roads across Bay of Plenty-Waikato will be busy with people visiting family and friends on these long weekends and [big events] are likely to add to the numbers. So we urge travellers to allow plenty of time for their journeys, drive to the conditions, and plan ahead before leaving home."
The NZTA website has interactive maps showing the busiest routes and times.
In one of a number of accidents yesterday, Wellington mayor Justin Lester escaped unscathed when his car and a truck collided. He was returning from a UN Holocaust Remembrance service at Makara Cemetery with his chief of staff Joseph Romanos, who was driving.
"I thought that was the end of it," Lester said. Neither was injured.
The forecast looks settled for much of the country. "Saturday looks like being the best we have had in a long time and it is looking good for holidaymakers well into next week," WeatherWatch analyst Aaron Wilkinson said.
"People shouldn't be fooled by a bit of cloud ... in the mornings because it will burn off by the afternoon" .
From Northland to Manawatu, including Coromandel, Bay of Plenty and the central high country, it is expected to be mainly fine.
"The Bay of Plenty and some inland areas of the Waikato could hit 27C and Hawke's Bay ... could reach the early 30s," Wilkinson said.
For Aucklanders, Anniversary Day is expected to be fine with light winds, but no rain.
That's good news for fans heading to events this weekend, including the Laneway Festival and the Buskers Festival in the CBD, Chinese New Year celebrations, and the Black Caps v Australia ODI at Eden Park.