Strong winds are hampering efforts to contain timber fires in Coromandel.
Fifty firefighters are battling multiple blazes at the Carter Holt Harvey mill at Kopu, near Thames.
Crews faced a chilly night with potentially hazardous gusty southwesterlies.
Fire and Emergency shift manger Daniel Nicholson says the weather made a serious situation even more serious as multiple large fires burned through timber, recycled materials, large amounts of wood shavings and bark.
Nicholson says fire crews are likely to remain at the mill for much of the day.
The fire broke out about 9.20pm.