Hurricane Dorian's core is "extremely dangerous" and will "continue to pound Grand Bahama Island" through much of Monday and Monday night, a Monday morning advisory from the National Hurricane Center (NHC) and Central Pacific Hurricane Center (CPHC) warned.

According to the advisory, Dorian "is moving toward the west near 1 mph (2 km/h)" and will slowly move westward to west-northwestward for the "next day or so," after which it is expected to turn gradually towards the northwest and north.

Dorian will "move dangerously close to the Florida east coast tonight through Wednesday evening," the advisory warned.

As of 5:00a.m. local time, the hurricane's core was approximately 40 miles (64 km) east of Freeport Grand, Bahama Island, with maximum sustained winds of 165mph (270 km//h).

"Although gradual weakening is forecast, Dorian is expected to remain a powerful hurricane during the next couple of days," the advisory added.

According to the Associated Press, Dorian, which hit the Bahamas as a Category 5 hurricane, tied with the 1935 Labor Day hurricane as the most powerful Atlantic hurricane to ever come ashore in the country.

The Bahamas have not yet provided information on casualties.

Dorian, which could bring a storm surge of 18 to 23 feet (5.5 to 7 meters) in some places, could impact over 20 million US citizens within the coming days.

On Sunday, Acting DHS chief Kevin McAleenan said the storm could skirt the US mainland but still cause major damage with heavy rainfall, high wind speeds, and a devastating storm surge.

Meanwhile, Florida, Georgia, and the Carolinas have declared a state of emergency, and US President Donald Trump issued a federal state of emergency for Florida.

Trump also canceled a scheduled trip to Poland last week, and has met emergency management officials.

Both South Carolina and Georgia have ordered a mandatory evacuation of the entire coast.