MetService's Chris Noble says Cyclone Cook is sitting northeast of Northland and tracking south-southeast and is expected to make landfall in Bay of Plenty by early evening.
By 6pm, it is expected to be just offshore before moving between Tauranga and Whakatane. It'll move south overnight and continue offshore toward the South Island on Friday.
Mr Noble says the strongest winds will likely hit between 7pm and 8pm just before Cyclone Cook makes landfall.
Police and the fire service have moved staff to areas likely to be hit ahead of time, including some of the smaller communities like Opotiki.
Civil Defence says if those communities become isolated, there'll be help for them ready to go.