Hurricane Maria intensified into a dangerous Category 5 storm and pounded the little island of Dominica as it surged into the eastern Caribbean on Monday night, and forecasters warned it might become even stronger.

The U.S. National Hurricane Center in Miami said Maria made landfall around 9:35 p.m. ET.

The storm was following a path that could take it on Tuesday near many of the islands already wrecked by Hurricane Irma and then head toward a possible direct strike on Puerto Rico on Wednesday.

The hurricane centre said Monday evening that Air Force Reserve hurricane hunter planes found that Maria had strengthened into a storm with 260 km/h winds.

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

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

Canadian travellers urged to avoid region

Hurricane warnings were posted for Guadeloupe, Dominica, St. Kitts, Nevis, Montserrat, Martinique, Puerto Rico, Culebra, and Vieques. A tropical storm warning was issued for Antigua and Barbuda, Saba, St. Eustatius and St. Lucia.

Other islands were warned to stay alert for changes in the storm. Hurricane watches were up in the U.S. and British Virgin Islands, Puerto Rico, the island shared by French St. Martin and Dutch St. Maarten, St. Barts and Anguilla.

As of Monday night, Global Affairs Canada advised people to avoid all travel to the following:

Anguilla.

British Virgin Islands.

U.S. Virgin Islands.

St. Maarten.

St. Martin.

Montserrat.

Saint-Barthélemy.

Martinique.

Saint Kitts and Nevis.

Saint Lucia.

Guadeloupe.

Dominica.

Puerto Rico.

The hurricane centre said the storm should begin to affect parts of the Leeward Islands by Monday night, with storm surge raising water levels by 1.8 metres near the storm's eye. The storm was predicted to bring up to 30 centimetres of rain across the islands, with more in isolated areas.

Maria could make a direct hit on Puerto Rico, which was spared the full brunt of Irma, though much of the island had its power knocked out.

Gov. Ricardo Rossello said officials had prepared about 450 shelters with a capacity for nearly 68,000 people — or even 125,000 in an emergency. He said schools were cancelled for Monday and government employees would work only a half day.

<a href="https://twitter.com/hashtag/Maria?src=hash">#Maria</a> is now a category 5 <a href="https://twitter.com/hashtag/hurricane?src=hash">#hurricane</a> with maximum sustained winds of 160 mph (260 km/h)- See the special advisory @ <a href="https://t.co/tW4KeGdBFb">https://t.co/tW4KeGdBFb</a> <a href="https://t.co/1G6WMaaVEx">pic.twitter.com/1G6WMaaVEx</a> —@NHC_Atlantic

Officials in the Dominican Republic urged people to leave areas prone to flooding and said fishermen should remain in port. The country's president, Danilo Medina, cancelled his speech before the UN General Assembly so that he can return home and co-ordinate preparations.

Farther north, long-lived Hurricane Jose continued to head northward off the U.S. 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 Massachusetts' Cape Cod.

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.

Meanwhile, tropical storm Lee weakened into a tropical depression far out in the Atlantic while Otis strengthened into a hurricane out in the Pacific. Neither threatened land.