HURRICANE Dorian has gained strength as an “extremely dangerous” Category 4 storm, bearing down on the north-western Bahamas en route to Florida’s east coast.

Millions of people in Florida, along with the state’s Walt Disney World and US president Donald Trump’s Mar-a-Lago resort, are in the potential crosshairs of the hurricane.

Forecasters say Dorian, which had top sustained winds of 140mph on Friday night, will threaten the Florida peninsula later tomorrow or early on Tuesday.

However, the National Hurricane Centre in Miami cautioned that its meteorologists remain uncertain whether Dorian will make a devastating direct strike on the state’s east coast or inflict a glancing blow.

Some of the more reliable computer models predicted a late turn northward that would see Dorian hugging the Florida coast.

“There is hope,” Weather Underground meteorology director Jeff Masters said.

The storm ratcheted up from a menacing Category 3 hurricane to an even more dangerous Category 4. That raised fears Dorian could become the most powerful hurricane to hit Florida’s east coast in nearly 30 years.

National Hurricane Centre projections showed Dorian hitting roughly near Fort Pierce, some 70 miles north of Mar-a-Lago, then running along the coastline as it moves north.

Forecasters cautioned that the storm’s track remains still highly uncertain and even a small deviation could put Dorian offshore – or well inland.

Mr Trump has declared a state of emergency in Florida and authorised the Federal Emergency Management Agency to coordinate disaster relief efforts. He told reporters that “Mar-a-Lago can handle itself” and that he is more worried about Florida.

As Dorian closed in, Labour Day weekend plans were upended.

Major airlines began allowing travellers to change their reservations without fees. The big cruise lines began rerouting their ships. Disney World and Orlando’s other resorts found themselves in the storm’s projected path.

Still, with Dorian days away and its track uncertain, Disney and other major resorts held off announcing any closings, and Florida authorities ordered no immediate mass evacuations.

“Sometimes if you evacuate too soon, you may evacuate into the path of the storm if it changes,” governor Ron DeSantis said.

Some counties announced mandatory evacuations on Friday. Brevard County and Martin County officials said residents of barrier islands, mobile homes and low-lying areas would be under a mandatory evacuation order beginning this morning.

The Brevard County order includes the Kennedy Space Centre. Indian River County officials said they will recommend residents of its barrier island voluntarily evacuate once hurricane warnings are issued.

Homeowners and businesses rushed to cover their windows with plywood. Supermarkets ran out of bottled water, and long queues formed at petrol stations, with some fuel shortages reported.

Early on Saturday, Dorian was centred 470 miles east of West Palm Beach. It was moving north-west at 12mph. Forecasters warned that its slow movement means Florida could face a prolonged battering of wind, storm surge and torrential rain.