Meanwhile, rainfall from what had been Tropical Storm Lee continued inundating a wide portion of Pennsylvania and other northeastern states, leaving at least seven dead.
Maria's maximum sustained winds early Friday were near 40 mph (65 kph), with some slight strengthening possible, according to the U.S. National Hurricane Center in Miami. The storm was centered about 435 miles (705 kilometers) east-southeast of the Leeward Islands and moving west-northwest near 18 mph (30 kph).
A tropical storm warning was in effect for a host of islands: Antigua, Anguilla, Barbuda, Montserrat, Nevis, St. Kitts, the British Virgin Islands, the U.S. Virgin Islands, Guadeloupe, St. Maartin, Saba and St. Eustatius.
A tropical storm watch was in effect for St. Barthelemy, St. Marteen, Martinique, Dominica, and Puerto Rico including Vieques and Culebra.
On its current forecast track, Maria's center would reach the Leeward Islands early Saturday and be near the Virgin Islands by Saturday night, the hurricane center said.
To the west, Tropical Storm Nate prompted a tropical storm warning on Mexico's coast from Chilitepec to Celestun. A tropical storm watch was in effect from Celestun to Progreso.
Nate's maximum sustained winds were near 65 mph (100 kph) and the hurricane center said the storm was expected to become a hurricane later in the day or on Saturday. Nate was centered about 115 miles (190 kilometers) west of Campeche, Mexico, and was nearly stationary early Friday.
Also in the Atlantic, Hurricane Katia was moving northeast over open water after passing between the U.S. and Bermuda. Despite not hitting land, the hurricane center said large swells generated by the Category 1 storm will continue affecting the U.S. East Coast and Bermuda.
Katia was centered about 395 miles (640 kilometers) north-northwest of Bermuda and was moving northeast near 24 mph (39 kph).