Civil Defence centres are bracing for the tail-end of the cyclone to whip the North East of the North Island tomorrow.
MetService expects Cyclone Pam to move south, bringing strong winds and rain to Northland and along the eastern coastline to Gisborne.
Although MetService said the cyclone would weaken from a category 5 to a category 2 storm by midnight tomorrow, it is still forecasting severe southeasterly gales and heavy rain for the north east tomorrow evening.
Forecaster David Miller was expecting a significant storm.
"So we have a heavy rain warning for Gisborne, northern Hawke's Bay and the ranges of eastern Bay of Plenty. We're expecting severe south-east gales with gusts of 160 kilometres of possibly more."
Bay of Plenty Civil Defence group controller Clinton Naude said they had been preparing for a few days.
"We've been working closely with the local councils and emergency services to make sure everyone is on alert and standby. Working with councils in terms of their contractors on hotpoints. We've also been working strongly to push out a message to the communities to get prepared."
MetService said rivers and streams in these areas would rise rapidly and slips and surface flooding were likely, making driving hazardous.
It said it was still tracking the cyclone which may change path by tomorrow afternoon, and people should regularly check its website for updates.
Mayor of Thames-Coromandel, Glenn Leach, said the area is bracing.
"We're just taking it as it comes, but we're still saying to everyone be prepared, get three days of water and food, and gas and batteries set up. Because it's only got to change course fractionally and we could be in for a hiding."