The Transport Agency expects more traffic backlogs on highways than usual this summer, because more New Zealanders are holidaying here than overseas.
It says people should allow extra time and keep their cool if they do encounter delays.
Wellington Transport Systems manager Mark Owen says people can look at New Zealand Transport Agency - Waka Kotahi website for forecasts of the busiest days, times and routes.
He encouraged people to plan ahead and drive to the conditions.
The AA said on that Sunday and Monday, the worst spots for holidaymakers leaving Auckland and Wellington were the Kapiti Coast, the Puhoi to Warkworth road and the road from Manukau to Drury.
"The best advice we can give motorists is to plan ahead and, if possible, avoid driving through these hotspots between around 10am and 4pm for the next week or so.
"Not everyone has that sort of flexibility, but if you can adjust your travel, you can save you and your family a lot of pain."