Hurricane Maria grew into a Category 3 storm as it barrelled toward a potentially devastating collision with islands in the eastern Caribbean. Forecasters warned it was likely to grow even stronger.

The storm was on a path that would take it near many of the islands already wrecked by Hurricane Irma and then on toward a possible direct strike into Puerto Rico on Wednesday as a Category 4 hurricane.

"This storm promises to be catastrophic for our island," said Ernesto Morales with the US National Weather Service in San Juan. "All of Puerto Rico will experience hurricane force winds."

The US territory imposed rationing of basic supplies including water, milk, baby formula, canned foods, batteries, flashlights and other items.

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The US National Hurricane Center said Maria had maximum sustained winds of 200km/h Monday afternoon (local time). It was centred about 70km east-northeast of Martinique - or 115km east-southeast of Dominica - and heading west-northwest at 17km/h.

Hurricane warnings were posted for the US and British Virgin Islands, Guadeloupe, Dominica, St. Kitts, Nevis, Montserrat, Martinique and St Lucia. A tropical storm warning was issued for Antigua and Barbuda, Saba, St Eustatius, St Maarten and Anguilla.

Forecasters said hurricane conditions should begin to affect parts of the Leeward Islands by late Monday (local time), with storm surge raising water levels by 1.8 to 2.7m near the storm's centre. The storm was predicted to bring 15 to 30cm of rain across the islands, with more in isolated areas.

Officials in Dominica closed schools and government offices on Monday and urged people to evacuate and seek shelters.

"We should not take this storm lightly," said Prime Minister Roosevelt Skerrit. "Let us continue to pray for our safety."

Officials in Guadeloupe said the French Caribbean island would experience extremely heavy flooding starting Monday afternoon, and they warned that many communities would be submerged overnight.

In nearby Martinique, authorities ordered people to remain indoors and said they should be prepared for power cuts and disruption in the water supply. All schools and non-essential public services were closed.

The storm has hurricane-force winds that extend about 24km from the eye, and tropical storm force winds out as far as 205km. The current forecast track would carry it about 35km south of St Croix in the US Virgin Islands late Tuesday and early Wednesday, according to territorial Governor Kenneth Mapp.

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"We are going to have a very, very long night," Mapp said as he urged people in the territory to finish any preparations.

St Thomas and St John are still recovering from a direct hit by Hurricane Irma, which did extensive damage and caused four deaths on the two islands.

Men remove a boat from the water ahead of Hurricane Maria in the Galbas area of Sainte-Anne on the French Caribbean island of Guadeloupe. Photo / AP
Men remove a boat from the water ahead of Hurricane Maria in the Galbas area of Sainte-Anne on the French Caribbean island of Guadeloupe. Photo / AP

On Wednesday, Maria was expected to be near or over Puerto Rico, which was spared the full brunt of Irma, although much of the island had its power knocked out. Nearly 70,000 people remain without power, and Governor Ricardo Rossello on Monday warned of another widespread outage.

Forecasters said the storm would dump up to 46cm of rain across Puerto Rico and whip the US territory with heavy winds for 12 to 24 hours.

Officials said the Federal Emergency Management Agency was ready to bring drinking water and help restore power in Puerto Rico immediately after the storm.

Rossello said officials had prepared about 450 shelters with a capacity for nearly 68,000 people - or even 125,000 in an emergency. There are still nearly 200 people in shelters from Hurricane Irma. Schools were cancelled for Monday and government employees would work only a half day.

Farther north, long-lived Hurricane Jose continued to head northward off the US East Coast, causing dangerous surf and rip currents. It wasn't expected to make landfall but tropical storm watches were posted along the coast from Delaware to Cape Cod, Massachusetts.

Jose was centred about 425km east-southeast of Cape Hatteras, North Carolina, and was moving north at 15km/h. It had maximum sustained winds of 120km/h.

The ocean washed over parts of North Carolina's Outer Banks as Hurricane Jose passed well to the east, and five people were knocked off a coastal jetty in Rhode Island by high surf caused by the storm. Officials said rescuers had to fight through rough surf to load the injured on to stretchers and get them to shore. All five were taken to a hospital with minor and major injuries.

In the Pacific, Tropical Storm Norma's threat to Mexico's Los Cabos resort area at the southern end of the Baja California Peninsula seemed to ease as forecasters said the storm's centre was likely to remain offshore.

Norma had winds of about 85km/h and it was centred about 280km southwest of Cabo San Lucas. The Baja California Sur state government prepared storm shelters and cancelled classes for Monday.

Meanwhile, Tropical Storm Lee weakened into a tropical depression far out in the Atlantic while Hurricane Otis weakened far out in the Pacific. Neither threatened land.

- AP