The storm is expected to strengthen over the next few days. Tracking shows the tropical storm will head to the north of New Zealand over the next 10 days. Latest modelling has suggested Storm Oma may well grow into a “severe” Category three storm or higher.
The storm is currently moving slowly towards New Zealand and is expected to take more than a week to reach the island.
Philip Duncan, from Weather Watch said: “That it is definitely a severe cyclone” and warned people to pay attention to it.
He added everyone should get used to flip-flopping forecasts as the storm is likely to connect with a cold front coming up from the south which could increase rainfall.
At the beginning of the week, flights from Australia are likely to go around the storm while shipping routes will be affected.
READ MORE: Tropical Cyclone Oma track: Category 2 tropical storm heads to Vanuatu
Vanuatu Meteorological Agency warned residents “damaging gale force winds of 75km/h” over the next 12 to 24 hours.
The regions most at risk are Torba, Sanma, Penama and Malampato.
Heavy rainfall and flash flooding are real threats, weather forecasters said.
The National Disaster Office placed the islands on red alert yesterday and this remains in place.
AccuWeather Senior Meteorologist Kristina Pydynowski said: “Rainfall through this weekend can total 100-200 mm (4-8 inches) across the island’s mountainous western areas.
“There can be an AccuWeather Local StormMax of 300 mm (12 inches) in the northern mountains.”
While the strongest wind gusts are expected offshore, the winds are still powerful enough to down tree branches and cause power outages.
Rip currents and rough seas could cause coastal flooding over the next few days.
People have been urged not to venture out in open water in the affected areas until the weather system has passed.