Vanuatu's Meteorological Service says there is a red alert in place today as Cyclone Oma approaches the country's northern provinces.
Damaging gale force winds of 75 km with gusts up to 100km are expected to affect Torba, Sanma and Penama provinces for the next 12 to 24 hours.
Heavy rainfall bringing flash flooding over low lying areas and river banks, as well as coastal floodings will affect the countries three northen most provinces today.
Head forecaster Fred Jockley said Cyclone Oma was expected to reach the northern provinces of Torba and Sanma today between midday and 6pm and it may yet intensify into a Category 2 system, before heading over cooler waters which would weaken its effects.
"The night shift forecasters have issued a red alert for especially Torba Province and Sanma Province. But for nine o'clock we will be including Penama and most probably Malampa. We'll see how fast the system moves closer to Sanma and Torba."
He said there was also a marine warning in force for the whole of Vanuatu, and that vessels are strongly advised not to go out as high seas are expected for northern and central coastal and open waters.
Mr Jockley said people needed to heed messages from the National Disaster Management Office to prepare themselves for the cyclone.
"For those who have not taken the warning seriously, they should start preparing themselves before the system actually comes over if it maintains its track of movement."
He said Shefa Province, which includes Vanuatu's capital Port Vila on the island of Efate, was likely to be impacted by Cyclone Oma within the next 24 to 48 hours but this would depend on how the system tracks.
Torba Province includes Banks and Torres Islands with a population of around 10,000 people and Sanma is home to 54,000 people mainly living on the islands of Santo and Malo.