A slip is causing traffic delays in Coromandel, while clean-up crews are tackling road damage caused by flooding north of Auckland.
The New Zealand Transport Agency said the slip, just south of Coromandel Town, was below the road and was being assessed by geotechnical exports today.
One lane of the road was closed and stop-go controls were in place, the agency said.
The road was closed to trucks and other heavy vehicles, which could cause more movement at the site, it said.
Heavy vehicles could use State Highway 25A as an alternative route.
Meanwhile, cleanup efforts were under way following heavy flooding north of Auckland.
Sustained rainfall caused flooding on rural roads from Warkworth to Wellsford yesterday, leaving a couple stranded on Wayby Valley Road and in need of rescue.
Fire crews also evacuated a family from their Wangaripo Valley home.
NZTA journey manager Jacqui Hori-Hoult said all roads were now open, but contractors were working to clear the damage caused overnight.
"On State Highway 1 we've had a tree slip so we'll be managing that and looking to remove that this evening," she said.
"On State Highway 16 there's been a small slip ... which has been cleared and our contractors are out making the pavement safe - there's a lot of damage to the pavement with regard to potholes."
Motorists should drive to the conditions because there was still a lot of surface water, Ms Hori-Hoult said.