From the north, traffic was building southbound on State Highway 1 through Wellsford and Warkworth, the New Zealand Transport Agency warned. Northbound was clear.
Traffic in Waikato was also causing delays on SH1 between Huntly and Taupiri, and was increasing on SH2 westbound between Maramarua and Mangatawhiri toward the Bombay Hills.
In Wellington, a crash shortly before 2pm near Forest Lakes Road had reduced lanes for a time, NZTA said, and warned to allow for extra travel time.
In the South Island, the coastal highway north of Kaikōura would remain closed for some time due to the earthquake damage, but SH1 south of the town was expected to be open in both directions from 6am to 8pm each day.
NZTA also warned of delays on SH7 between Hope River Bridge and the Lewis Pass summit.
MetService has issued a severe weather watch for heavy rain from Taranaki east as far as Taupō and south as far as Horowhenua.
Overnight in Auckland, SH1 between Manukau and Takanini was scheduled to be closed from 10pm until 6am tomorrow, along with the onramp to Redoubt Rd from 9pm.
A full motorway closure of SH20 from Lambie Drive to SH1 southbound was also scheduled from 10pm to 6am, with northbound motorists unable to turn right into Kirkbridge Rd.