“Potentially life-threatening” storm surges, destructive waves, flash floods and mudslides threatened the Leeward Islands — the island group that includes Martinique, Puerto Rico and the US and British Vigin islands — the NHC said.
“The eye and the intense inner core is expected to pass near Dominica in the next few hours,” the centre warned in its 2100 GMT (2:30 am IST) bulletin, describing Maria as “an extremely dangerous major hurricane”.
The French Caribbean island of Guadeloupe — the bridgehead for aid for Irma-hit French territories — ordered all at-risk zones to be evacuated.
The order, effective from 4 pm local time, bars specific areas considered to be at risk of “flooding, submersion and landslips,” according to the statement, issued by the island’s prefect.
Islanders on Martinique, which is also part of France, were ordered to stay indoors under a maximum-level “violet” alert.
As heavy rain beat down, energy supplier EDF said power had been cut off from 16,000 homes on Martinique, which has a population of some 400,000.
Dominica, St Kitts and Nevis, St Lucia and the British island of Montserrat are also on alert.
In Pointe-a-Pitre, Elodie Corte, the boss of a metalworking company, said there had been frantic preparations to limit the damage from the storm.
“We spent the morning strapping down the aluminium to stop it from flying away if the winds are strong,” she said.
But she worried that the torrential rains forecast could flood her home.
“We’ll seal everything as tightly as we can and then we’ll certainly go and stay with friends for the night,” she said.
Criticised for the pace of relief efforts in their overseas territories devastated by Irma, Britain, France and the Netherlands said they were boosting resources for the Caribbean as Maria approaches.
“We are planning for the unexpected, we are planning for the worst,” said Chris Austin, head of a UK military task force set up to deal with Irma, as the British Virgin Islands readied for the storm.
On the island of St Martin, which is split between France and the Netherlands, authorities announced a red alert ahead of Maria’s arrival.
“We’re watching its trajectory very closely, and we’re preparing for the worst-case scenario,” said local official Anne Laubies.
The Dutch navy tweeted that troops were heading to the two tiny neighbouring islands of Saba and St Eustatius to ensure security following widespread complaints of looting and lawlessness on St Martin after the first hurricane.
French Interior Minister Gerard Collomb said 110 more soldiers would be deployed to the region to reinforce about 3,000 people already there shoring up security, rebuilding infrastructure and distributing aid.
But he warned of “major difficulties” if Guadeloupe is hard hit, noting the territory was “the logistical centre from where we could supply St Martin and organise all the airlifts”.
Maria is due to sweep over the south of Sint Maarten — as the Dutch side of St Martin is called — today. The island was among the worst hit by Irma, with 14 killed.
Air France, Air Caraibes and Corsair have cancelled flights in and out of Martinique and Guadeloupe.