New Zealanders are evacuating towns along North Island's north-east coast, ahead of what is being called the worst storm in generations.
Cyclone Cook is expected to make landfall at 18:00 local time (06:00 GMT) over Bay of Plenty.
Authorities have warned of high waves, storm surges, and landslides.
It comes after severe floods caused by the remnants of Cyclone Debbie hit some parts of the country last week.
Parts of New Zealand's North Island are now under a state of emergency, with residents in the low-lying parts of Coromandel, which has already seen landslips and closed roads, told to leave immediately.
Cyclone Cook, which is forecast to bring winds of up to 150km/h (93 mph), is then expected to hit South Island on Friday.
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The BBC's Hywel Griffith says Bay of Plenty, which suffered flooding last week caused by the tail end of Cyclone Debbie, is expecting 300mm (11in) of rain to fall, which means some houses may be flooded again.
One local, Ian Jenkins, was fishing on Lake Taupo together with his wife when they saw a swirling storm approach across the water.
"It was very calm, hardly a breeze" when suddenly the weather began to change, he told the BBC.
Schools and businesses across the island have been shut early while residents in Auckland, which has already seen flooding, have been stocking up on emergency supplies.
The New Zealand military and emergency service teams are on standby. Flights across the country have either been delayed or cancelled, and national carrier Air New Zealand has suspended operations from Tauranga Airport in North Island.
The cyclone formed around Vanuatu on Sunday and moved towards New Caledonia, bringing heavy rain and winds and causing cuts to power and water supplies. One man died in New Caledonia when he was trying to cross a river to a friend's home.
New Zealand weather officials say that Cyclone Cook will be the worst to hit the country since 1968.
They have also warned that it is a "really tightly packed cyclone" that will bring a "phenomenal" amount of rain and wind, reported The New Zealand Herald, compared to Cyclone Debbie which was more spread out.
Cyclone Debbie hit Australia at the end of March, before its remnants drifted towards New Zealand, bringing large amounts of rain that caused severe flooding.
It soaked New Zealand cities like Wellington and Auckland and prompted the entire town of Edgecumbe to be evacuated.
Authorities are now worried about how Cyclone Cook will impact land that is already saturated from heavy rains.golden slot มือถือ