ST. PETERSBURG, Fla. -- Forecasters say Hurricane Maria became a Category 5 storm as the eye neared Dominica.

11 p.m. update: The eye of Hurricane Maria is moving over Dominica as a Category 5 storm with maximum sustained winds at 160 mph moving west-northwest at 9 mph.A hurricane warning is in effect for Guadeloupe, Dominica, St. Kitts, Nevis, and Montserrat, U.S. Virgin Islands, British Virgin Islands, Puerto Rico, Culebra, and Vieques.

The National Hurricane Center in Miami said Monday evening that Air Force Reserve hurricane hunter planes found that Maria had strengthened into a storm with 160 mph (260 kph) winds.

The hurricane is about 15 miles (25 kilometers) east-southeast of Dominica and moving west-northwest at 9 mph (15 kph).

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Several islands -- many of which were ravaged by Hurricane Irma earlier in the month -- are under a hurricane warning: the U.S. Virgin Islands, Guadeloupe, Dominica, St. Kitts, Nevis, Montserrat and Martinique. Hurricane watches, in addition to tropical storm warnings and watches, are in effect as well.

Hurricane Maria has become a major hurricane as it churns through the Caribbean islands last hit by Hurricane Irma.

Maria is forecast to sweep across the islands before a possible midweek landfall as a major, Category 3 or higher hurricane in Puerto Rico.

More: Saffir-Simpson hurricane scale: How to measure a tropical cyclone's strength

Related: Hurricane season: What's a watch, what's a warning?

It's expected Maria will take a turn to the north and east away from Florida and any possible U.S. impacts. However, the forecast uncertainty grows later in the week -- we cannot yet completely discount a threat to the mainland U.S.

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