The New Zealand Transport Agency (NZTA) predicts traffic will be at its heaviest until 4.30pm today between Puhoi and Wellsford. Congestion is not expected to ease until after 6pm.
Drivers are urged to avoid peak traffic times or plan for the delays.
South of Auckland long delays are forming between Rotorua and Manukau.
NZTA's Auckland traffic dashboard indicates the journey could take up to six hours, but Google traffic updates time the journey as taking around three hours.
Traffic is particularly congested on State Highway 1 between Hamilton and Taupiri, according to NZTA's dashboard.
On State Highway 1 between Bombay and Auckland CBD the journey is expected to take around 11 minutes longer than usual.
Meanwhile, most traffic surrounding the capital is free-flowing.
No delays are yet reported on NZTA's traffic dashboard for Hutt Valley, Wairarapa and Wellington.
A 15-minute delay between Levin and Waikanae is being reported by NZTA due to congestion in Otaki.
Traffic is picking up southbound from Ōtaki to Peka Peka and it's expected to last until 6pm.
Motorists are urged to be cautious on State Highway 2/Remutaka Hill Road as Metservice issues a strong wind warning.