(AFP) - A "catastrophic" Hurricane Milton was closing in on the storm-battered state of Florida on Wednesday as US officials pleaded with residents to flee or risk dying.

President Joe Biden warned that the Category 5 storm could be the worst natural disaster to hit the state in a century.

As the second huge hurricane in as many weeks rumbled toward Florida's west coast, people raced to board up homes and flee.

"It's a matter of life and death, and that's not hyperbole," Biden said from the White House on Tuesday, urging those under orders to leave to "evacuate now, now, now."

By Wednesday morning (0900 GMT) Milton was located 300 miles (485 km) southwest of Tampa, generating maximum sustained winds of 160 mph (260 kph), according to the National Hurricane Center (NHC).

"Milton remains a catastrophic Category 5 Hurricane," said the NHC, forecasting the storm to make landfall on the Florida Gulf coast late Wednesday night.

It "is expected to remain an extremely dangerous major hurricane when it reaches the west-central coast of Florida," it said.

Tampa city mayor Jane Castor warned residents on CNN: "If you choose to stay in one of those evacuation areas, you are going to die."

At a news conference, Governor Ron DeSantis ticked off town after town in danger.

"Basically the entire peninsula portion of Florida is under some type of either a watch or a warning," he said.

Airlines put on extra flights out of Tampa, Orlando, Fort Myers and Sarasota, as highways clogged up with escaping traffic and gas stations sold out of fuel.

- Walls of water -

Hurricane expert Michael Lowry warned that in the Tampa area, home to about three million people, Milton's storm surge "could double the storm surge levels observed two weeks ago during Helene," which brought massive flooding.

Biden postponed a major trip to Germany and Angola to oversee the federal response, as storm relief efforts have emerged as a political battleground ahead of the November 5 presidential election.

Donald Trump has tapped into frustration about the emergency response after Hurricane Helene and fueled it with disinformation, falsely claiming that disaster money had been spent instead on migrants.

Biden slammed Trump's comments as "un-American," while Vice President Kamala Harris warned about the danger that misinformation posed to the federal response.

"It's crude. Have you no empathy, man, for the suffering of other people? Have you no sense of purpose if you purport to be a leader?" she said, challenging Trump directly, during an interview with late-night talk show host Stephen Colbert.

In a scene of frantic preparation repeated all over Florida, dozens of cars lined up at a sports facility in Tampa to pick up sandbags to protect their homes from flooding.

John Gomez, 75, ignored official advice and traveled all the way from Chicago to try to save a second house he has in Florida.

"I think it's better to be here in case something happens," Gomez said waiting in line.

But Katie, in her 30s, heeded the call to evacuate and arrived in Orlando with her five-year-old son and dog from St. Petersburg, a coastal city where Hurricane Helene had brought three feet of floodwater into her bayside home two weeks ago.

Normally she would ride out the storm at a friend's elevated apartment, she told AFP, "but I'm not taking any chances this time around."

- Global warming factor -

Scientists say global warming has a role in intense storms as warmer ocean surfaces release more water vapor, providing additional energy for storms, which exacerbates their winds.

A report by the World Weather Attribution group published Wednesday said Hurricane Helene's torrential rain and powerful winds were made about 10 percent more intense due to climate change.

Storms of Helene's magnitude were formerly anticipated once every 130 years, but now the probability is closer to once every 53 years, on average.

On the ground, communities hit by deadly Hurricane Helene -- which slammed Florida late last month -- have rushed to remove debris that could become dangerous projectiles as Milton approaches.

In Mexico's Yucatan, strong winds toppled trees and pylons, and heavy rain caused flooding, but the peninsula avoided major damage or casualties as the storm barreled offshore.

Across the southeastern United States, emergency workers are still struggling to provide relief after Helene, which killed at least 230 people across several states.

It hit the Florida coastline on September 26 as a major Category 4 hurricane, causing massive flooding in remote inland towns in states farther north, including North Carolina and Tennessee.

Helene was the deadliest natural disaster to hit the US mainland since 2005's Hurricane Katrina, with the death toll still rising.

© Agence France-Presse