The NZ Transport Agency says sections of State Highways 1 and 10 in Northland have been closed by flooding.
SH1 near the Rangiahua Bridge is closed, and SH10 near the community of Kaeo is closed. Flooding at Kaeo could be made worse by a high tide at midday.
The closures will remain in place until this section of the highway is safe for drivers, says the NZTA's Regional Asset Manager, Steve Mutton.
Other sections of the state highway network in Northland remain open, by the NZTA says there is widespread surface flooding and traffic is down to one lane in some places.
"We urge everyone to drive to the conditions, and drive with extreme care and allow more time for their journeys so that there is no need to rush," says Mr Mutton. "Our contractors are working with emergency service to ensure the highways can remain open, and diversions are in place where needed."
The NZTA says it has been advised more heavy rain for the region is expected this afternoon.