Heavy rain has brought flooding that has closed State Highway 1 near Cape Rēinga at the top of the North Island.
The closure was just north of Waitiki Landing, at the turnoff to Te Hāpua, New Zealand's northernmost settlement.
Te Hāpua was still accessible but NZ Transport Agency Waka Kotahi (NZTA) was warning motorists there were no alternative routes to Te Paki or to the cape.
Northland Regional Council rainfall data shows the heaviest falls in the Kaitāia and Doubtless Bay areas, with the highest rate - 25mm of rain in an hour - recorded at Pukenui, 50km north of Kaitāia, between 11am and noon on Tuesday.
Heavy rain was also falling in Whangārei and in Dargaville, where residents were reporting significant surface flooding.
Serious rain had yet to hit the Bay of Islands.
MetService issued a heavy rain watch and a severe thunderstorm watch for all areas north of Whangārei until midnight.
The forecaster said thunderstorms and localised downpours were possible, especially in northern and western parts of the region.
Meanwhile, NZTA continued to urge motorists to take extra care at four trouble spots on Northland's state highways.
The roading agency said flooding was possible on SH1 at Rangiahua, west of Ōkaihau, and at Whakapara, north of Whangārei, as well as on SH10 at Kāeo.
More slips were possible on SH1 at Mangamuka Gorge, south of Kaitāia, which was still down to one lane after Sunday's big slip closed the road for more than 24 hours.
Temporary road surfaces on SH1 at Whakapara and Akerama, where major road rebuilding projects were underway north of Whangārei, could also be affected by heavy rain.
NZTA warned that large potholes could form anywhere and floodwaters could hide branches or other hazards.
Flooding just 30cm deep could be enough to sweep away vehicles, the agency said.
