Residents across the state emptied store shelves of water and household items.

The approaching storm also forced Nasa to roll its giant Artemis 1 moon rocket off its Cape Canaveral lauchpad after postponing the mission for a third time.

Ian, currently a Category 1 hurricane, is expected to make landfall in Cuba on Monday evening. After crossing the island, it could either make landfall north of Tampa Bay early on Friday or turn northwest towards Florida’s Panhandle, forecasters said.

“This is a really big storm,” Florida Governor Ron DeSantis said during a Monday news conference, noting that the storm could potentially envelope both coasts of the state.

For several years, Florida has experienced firsthand how climate change is making hurricanes wetter, windier and altogether more intense. There is also evidence that it is causing storms to travel more slowly, meaning they can dump more water in one place.

Signs of the impending storm were seen throughout the state of 21 million people. In Titusville, a city of 43,000 on the Atlantic Coast, crews used chainsaws to trim palm trees.

In a grocery store in St Petersburg, across the state on the Gulf Coast, only empty cardboard boxes remained where the store normally stocks distilled water. But toilet paper, snacks and canned soup were still available.

In historic Ybor City, a Tampa neighbourhood just northeast of downtown, Diane Zambito said she normally doesn’t get rattled by hurricanes that hit the state.

“But this one’s different,” she said. “This one scares me. It’s too big to not be scared if you have any sense.”

With no evacuation orders for her neighbourhood, Zambito and her husband were preparing to ride out the storm at home.

“We’re ready, I think,” Zambito said Monday afternoon as her husband hammered plywood over all the windows of their home. Later they planned to shovel sand into bags to stack up in front of the doors and prevent water from coming inside.

The Zambitos were among many Florida residents preparing for flooding from torrential rains that could submerge streets and homes. Hurricane-force could damage or destroy homes and businesses, and trigger power outages in the coming days, forecasters warn.

“We’re doing all we can to make sure this house holds up,” Zambito said.

The governor has mobilised 5,000 members of the National Guard while an additional 2,000 are coming from Tennessee, Georgia and North Carolina, with other nearby states having troops on standby.

STORM INTENSIFYING

The intensifying storm was about 160 km southwest of Grand Cayman on Monday morning with sustained winds of 128km per hour. It was on course to bisect Cuba on Tuesday on its way to Florida, the US National Weather Service said.

Ian should intensify once it enters the Gulf of Mexico, mushrooming into a Category 3 storm, but it could weaken again to Category 1, with winds of 90mph, while parked off Tampa on Florida’s Gulf Coast on Thursday. From there, Ian’s path is highly uncertain, forecasters said.

A deluge is all but certain. Between 15cm and 30cm of rain will inundate both Florida’s Gulf and Atlantic coasts on Thursday, said Bob Oravec, a meteorologist with the National Weather Service’s Weather Prediction Center in College Park, Maryland.

Ian follows Hurricane Fiona, a powerful Category 4 storm that carved a path of destruction last week through Puerto Rico, leaving most of the US territory without power and potable water. Fiona then barrelled through the Turks and Caicos islands, skirted Bermuda and slammed into Canada’s Atlantic coast, where critical infrastructure might take months to repair.

(Reporting by Shannon Stapleton and Brendan O’Brien.)