Florida Governor Rick Scott warned Friday that all of the state's 20 million inhabitants should be prepared to evacuate as Hurricane Irma bears down for a direct hit on the southern U.S. state.

"The storm is powerful and deadly," Scott said. "Do not ignore evacuation orders.

King Willem-Alexander of the Netherlands will visit the island of Curacao on Sunday to witness first-hand the aid operation for hurricane-hit territories, and may travel to stricken St Martin, Dutch officials said.

Hurricane Jose strengthened to a Category Three storm Thursday, as it followed in the path of monster Hurricane Irma, U.S. weather forecasters said.

Damage caused by Hurricane Irma on French islands in the Caribbean is estimated to be "much higher" than 200 million euros ($240 million), a state insurance group said on Friday. 

At least one person was killed and "several were injured" after Hurricane Irma raged over Dutch Sint Maarten in the Caribbean, Internal Affairs Minister Ronald Plasterk said Thursday.

Hurricane Jose, a Category 1 storm packing winds of about 135 kilometers per hour (85 miles per hour), is approaching the Caribbean hot on the heels of Irma, but will likely bypass land, according to the French weather service.

Hurricane Irma will have a "truly devastating" impact when it slams into southern coastal areas of the United States, the head of the US emergency agency said on Thursday

"The majority of people along the coast have never experienced a major hurricane like this. It will be truly devastating," Federal Emergency Management Agency (FEMA) chief Brock Long told CNN.

Britain is sending two military vessels to help victims of Hurricane Irma and is earmarking £32 million ($41.8 million, 34.8 million euros) in aid, the government said Thursday.

Hurricane Irma, rampaging across the Caribbean towards the Bahamas and south Florida, is smashing not only homes and hotels but weather records as well.

The French part of the Caribbean island St Martin is "95 percent destroyed" after Hurricane Irma tore through the region, top local official Daniel Gibbs said late Wednesday.