After devastating islands in the Caribbean and leaving around a dozen people dead, Hurricane Irma is powering towards landfall on the United States mainland, with residents of South Florida being told that homes may not be inhabitable for weeks or months after the storm passes through.

Having caused untold damage on islands such as Barbuda, and the Virgin Islands as a Category 5 hurricane. Irma also left more than a million people in Puerto Rico without power.

“This is a nuclear hurricane,” Miami Beach Mayor Philip Levine said, urging residents of his barrier reef town to evacuate. Residents “should leave the beach, they must leave the beach”.

The low-lying British territory of the Turks and Caicos Islands sit in the path of the storm, and could see storm surges of up to 6m while it is also heading for the Bahamas and skirting Cuba into Friday

In response to the unfolding crisis, Prime Minister Theresa May announced that £32m had been released to assist the relief effort, with Britain being one of a number of nations to send money and ships carrying supplies to the region.

The confirmed fatalities include an infant on Barbuda, one person in the British territory of Anguilla, three people in Puerto Rico, four in the US Virgin Islands, and one in St Maarten, the Dutch side of an island shared with Saint Martin, a French territory. The French government have reduced the number of fatalities in Saint Martin from eight down to four.

Barbuda “is literally rubble,” Prime Minister Gaston Browne of Antigua and Barbuda said.

“The essential point is that our main infrastructure has stood up and our country can resume normal life within hours,” he said, perhaps inaccurately as 95 per cent of Barbuda infrastructure was later deemed to have been damaged.

Reports of damage in the US and British Virgin Islands also began to emerge after the storm passed through on Wednesday. Residents there reported that roofs had been blown off, and that they had seen a deluge of rain accompanied by harsh winds that ripped all of the leaves off of trees, leaving behind a scene of apocalyptic emptiness.

Islands like Barbuda face the extra fear of another hurricane, Jose, coming behind Irma. Jose was upgraded to a category 3 hurricane, with sustained winds of 120mph, on Thursday and Barbuda, the British Virgin Islands and a number of other locations could see it hit in 48 hours. The British Virgin Islands Governor Gus Jaspert has declared a state of emergency in the wake of Irma – and with Hurricane Jose threatening to reach them this weekend.

Mr Jaspert asked people on the British Virgin Islands to avoid using roads unless “absolutely necessary” in order to prioritise emergency services.

As for Irma – which now holds the record for the most hours with sustained winds of 180mph and higher – the latest advice from the US National Hurricane Centre (NHC) updated its path to show it having shifted about 20 miles to the west, which would mean a direct hit for Miami.

Communities in southern Florida are preparing for that potential landfall of one of the most powerful storms in recorded history, stocking up on vital supplies like water and non-perishables. Reports have swirled of long lines forming for petrol – an increasingly rare commodity in the state – as residents begin their evacuations away from the zones that may be hit hardest by potential landfall of Irma.

Mandatory evacuations have already been ordered along the potential path of the hurricane, including for more than 100,000 residents in Miami-Dade County, all of Palm Beach Island, parts of Broward County, and Monroe County. Mandatory evacuations have also been issued in coastal Georgia as well.

Florida Governor Rick Scott issued a state of emergency for the entire state of Florida earlier in the week, while Georgia Governor Nathan Deal has issued a similar state of emergency for 30 counties in his state.

Barbuda, Hurricane Irma – in pictures Show all 7 1 /7 Barbuda, Hurricane Irma – in pictures Barbuda, Hurricane Irma – in pictures A roof-less house in Barbuda ABS TV Barbuda, Hurricane Irma – in pictures A mobile network tower snapped in two by the hurricane ABS TV Barbuda, Hurricane Irma – in pictures The hurricane left debris strewn across the island Barbuda, Hurricane Irma – in pictures Rubble in the aftermath of the hurricane ABS TV Barbuda, Hurricane Irma – in pictures The destruction in Barbuda, as seen from an ABS TV helicopter ABS TV Barbuda, Hurricane Irma – in pictures As well as destroying most houses, the hurricane also left plenty of flooding ABS TV Barbuda, Hurricane Irma – in pictures Barbudan residents survey the damage ABS TV

“So take this seriously. Leave now, don’t wait,” Mr Scott said during a press briefing on Thursday. “It’s wider than our entire state and could cause major and life-threatening impacts on both coasts.”

President Donald Trump, eyeing what could be the second major natural disaster of his presidency, praised the work of the Federal Emergency Management Agency, and said that the National Guard has saved more than 14,000 lives in Texas, where Hurricane Harvey brought devastating winds and rains last week.

“I can say this: Florida is as well-prepared as you can be for something like this, and now it’s just a question of what happens,” Mr Trump said. “It’s the largest hurricane we’ve ever seen coming out of the Atlantic, and the winds are the strongest that we’ve ever seen from a hurricane in the region.”

Mr Scott had already activated 100 Florida National Guard members as of Thursday, and all 7,000 members are expected to report for duty on Friday.

Hurricane Irma is the second storm in recorded history to sustain winds at 185mph for 24 hours straight.

At least 31,000 people fled the Florida Keys, which could begin seeing wind and rain from Irma as early as Friday night.

“It is wider than our entire state and could cause major and life-threatening impacts from coast to coast. Regardless of which coast you live on, be prepared to evacuate,” Mr Scott said.

Other states that could see damage from Irma as it travels up the US coast are making preparations. Georgia Governor Nathan Deal ordered evacuations for all areas east of Interstate 95, including the city of Savannah, and authorised about 5,000 National Guard members to help with response and recovery. Mr Trump declared a state of emergency for South Carolina.

Noel Marsden said he, his girlfriend, her son and their dog left Pembroke Pines north of Miami with plans to ride out Irma in Savannah, only to find the city was also shutting down because of the storm.

“I’ve got a buddy in Atlanta and a buddy in Charlotte. We’ll wind up one of those two places because there are not hotels, I can tell you that,” he said.

Irma’s eventual path and Florida’s fate depends on when and how sharp the powerful hurricane takes a right turn, National Weather Service Director Louis Uccellini said.

“It has become more likely that Irma will make landfall in southern Florida as a dangerous major hurricane,” the NHC said.