People across Florida have been warned that a tropical storm off the coast of Mexico could intensify rapidly into a major hurricane over the coming days before hitting the storm-ravaged Gulf Coast in the US.

“There is increasing confidence that a powerful hurricane with life-threatening hazards will be affecting portions of the Florida west coast around the middle of this week,” senior hurricane specialist Eric Blake advised on Sunday.

While forecast models for the storm – named Milton – vary widely, the most likely path suggests it could make landfall on Wednesday just north of Tampa Bay and remain a hurricane as it moves across central Florida into the Atlantic Ocean, largely sparing other south-eastern states ravaged by Hurricane Helene.

Helene caused catastrophic damage from Florida into the Appalachian mountains and a death toll that rose on Sunday to 230 people.

Florida governor Ron DeSantis said on Sunday that while it remains to be seen just where Milton will strike, it is clear that Florida is going to be hit hard.

He said: “I don’t think there’s any scenario where we don’t have major impacts at this point.”

He added: “You have time to prepare – all day today, all day Monday, probably all day Tuesday to be sure your hurricane preparedness plan is in place. If you’re on that west coast of Florida, barrier islands, just assume you’ll be asked to leave.”

Mr DeSantis expanded his state of emergency declaration on Sunday to 51 counties, and said Floridians should prepare for more power outages and disruption, making sure they have a week’s worth of food and water and are ready to hit the road.

The Federal Emergency Management Agency, meanwhile, co-ordinated with the governor and briefed US President Joe Biden.

Kevin Guthrie, executive director of the Florida Division of Emergency Management, said: “We are preparing… for the largest evacuation that we have seen, most likely since 2017, Hurricane Irma.”

The state has prepared emergency fuel sources and EV charging stations along evacuation routes and “identified every possible location that can possibly house someone along those routes”, Mr Guthrie said.

As many as 4,000 National Guard troops are helping state crews to remove debris, Mr DeSantis said, and he directed that Florida crews dispatched to North Carolina in Helene’s aftermath return to the state to prepare for Milton.

Tropical Storm Milton’s centre was about 860 miles west-southwest of Tampa, Florida, early Sunday, heading east at 5mph with maximum sustained winds of 60mph, the National Hurricane Centre in Miami said.

The hurricane centre said Mexico’s Yucatan peninsula, the Florida Peninsula, the Florida Keys and the north-western Bahamas should monitor the system’s progress.

Meanwhile in the open Atlantic, Hurricane Kirk diminished to a Category 2 hurricane on Sunday, with top winds of 105mph, sending large swells and “life-threatening surf and rip current conditions” to Bermuda and northward along the US and Canadian coasts, the centre said.

Hurricane Leslie was also moving over the Atlantic Ocean, well away from land, with top winds of 85mph.