0401 GMT December 14, 2017
Irma – which has killed at least 19 people and devastated thousands of homes in the Caribbean – made landfall late Friday on the Camaguey Archipelago of Cuba as a maximum-strength Category 5 storm, AFP reported.
The hurricane weakened slightly to a Category 4 hours later, swirling some 245 miles (395 kilometers) away from Miami and packing still powerful maximum sustained winds of 155 miles per hour, according to the US National Hurricane Center.
In Cuba officials reported "significant damage" in parts of the island's center without providing further details, but said there were not yet casualties.
More than a million people on the Caribbean's largest island have evacuated as a precaution, authorities said.
Irma is expected to strike the Florida Keys Sunday before moving inland, and many residents have joined a mass exodus amid increasingly dire alerts to leave.
"Irma remains an extremely dangerous hurricane!" tweeted the National Weather Service early Saturday.
"It's not too late to get off the Keys!!!" the agency said. "You still have time, this morning, to get out! Please, the Keys are not safe."
According to Florida's Division of Emergency Management some 5.6 million residents have been ordered to evacuate – nearly a quarter of the state population.
Warning that Irma would be worse than Hurricane Andrew – which killed 65 people in 1992 – Florida's governor said all 20.6 million Floridians should prepare to flee.
"If you're in an evacuation zone, you should be very cautious, you should get out now," Governor Rick Scott told CNN. "This is a powerful storm bigger than our state."
Bumper-to-bumper traffic was snaking north out of the peninsula, with mattresses, gas cans and kayaks strapped to car roofs.
The storm ravaged a series of tiny islands before slamming into the Virgin Islands and Puerto Rico.
French state-owned reinsurer CCR estimated Irma had caused 1.2 billion euros ($1.4 billion) worth of damage to homes, vehicles and businesses in the territories of Saint Martin and Saint Barts, AFP reported.
"This amount covers damages to homes, vehicles and businesses" insured for natural disasters, CCR said in a statement.
The disaster is "one of the worst experienced by France in 35 years," it said.
CCR chief Bertrand Labilloy said Friday that the reinsurer had "sufficient reserves to cover the disaster whatever the cost."
The overall damage across the Caribbean has been estimated at more than $10 billion.
Sint Maarten, the Dutch part of St Martin, has suffered $2.5 billion in damage, according to the Center for Disaster Management and Risk Reduction Technology (CEDIM) in Germany.
Meteorologists meanwhile were closely monitoring two other Atlantic storms.
Jose, another powerful Category 4 storm, was heading towards the same string of Caribbean islands Irma has pummeled in recent days.
Katia made landfall in eastern Mexico late Friday – just as the country was grappling with its worst earthquake in a century – as a Category 1 hurricane.