Residents near Dargaville are being told they may need to evacuate if wind pushes an out-of-control fire towards their homes.
The fire in the hills above Kellys Bay, on the eastern side of the Poutou Peninsula, has been burning since Monday night.
It has already destroyed more than 200 hectares of pine forest, and is only partially contained.
Conservation Department spokesperson Sue Reed-Thomas said residents were being keep up-to-date about the dangers.
"The weather conditions are expected to change overnight so an increase in wind.
"The worst case scenario will include evacuating people from the area to ensure that they're safe."
Kellys Bay, on the Kaipara Harbour, has a camping ground, and about 40 homes and baches.