A heavy rain watch has been issued for the North Island on Tuesday as the dregs of former-cyclone Debbie wash across from Australia.
The Transport Agency is warning drivers to be cautious over the next two days with heavy rain forecast.
The storm is set to hit the central and lower North Island after devastating much of Queensland in Australia and NZTA spokesman Mark Owen says the 400 millimetres of rain will be disruptive.
"There is a chance that we'll get some slips coming down, potentially trees could come down. We've got crews out monitoring the road so they'll be keeping an eye on things.
"Drivers do just need to be aware that with the rainfall that's expected there is the chance of surface flooding and debris on the roads in some places."
MetService meteorologist Cameron Coutts told The AM Show that said some parts of the country have already experienced heavy rain.
"We've got a trough of low pressure across the lower North Island and that's producing rain at the moment.
"They've had about 60 millimetres in 12 hours in parts of the hill country of Whanganui and Taranaki and that's going to continue today."
MetService said the weather system will take around 3 days to pass over New Zealand, leaving for a much improved weekend outlook.