FLORIDA, United States (AP) — Florida residents living in vulnerable coastal areas were ordered to pack up and leave Tuesday as Hurricane Idalia gained steam in the warm waters of the Gulf of Mexico and threatened to unleash life-threatening storm surges and rainfall.

Idalia also pummelled Cuba with heavy rains on Monday and Tuesday, leaving the tobacco-growing province of Pinar del Rio underwater and many of its residents without power.

Idalia had strengthened to a Category 2 system on Tuesday afternoon with winds of 100 mph (155 kph). The hurricane was projected to come ashore early Wednesday as a Category 3 system with sustained winds of up to 120 mph (193 kph) in the lightly populated Big Bend region, where the Florida Panhandle curves into the peninsula. The result could be a big blow to a state still dealing with lingering damage from last year’s Hurricane Ian.

The National Weather Service in Tallahassee called Idalia “an unprecedented event” since no major hurricanes on record have ever passed through the bay abutting the Big Bend.

In Tarpon Springs, a coastal community north-west of Tampa, 60 patients were evacuated from a hospital out of concern that the system could bring a 7-foot (2.1-metre) storm surge.

Idalia’s initial squalls were being felt in the Florida Keys and the south-western coast of Florida on Tuesday afternoon, including at Clearwater Beach. Workers at beachside bars and T-shirt shops boarded up windows, children skim-surfed the waves, and hundreds of people watched the increasingly choppy waters from the safety of the sand.

After landing in the Big Bend region, Idalia is forecast to cross the Florida peninsula and then drench southern Georgia and the Carolinas on Thursday.

At 5:00 pm Tuesday, Idalia was about 195 miles (310 kilometres) south-west of Tampa, the National Hurricane Center said. It was moving north at 16 mph (26 kph).

In Cuba, meanwhile, Idalia left more than 60 per cent of Pinar del Rio’s residents in the dark, State media reported.

“The priority is to re-establish power and communications and keep an eye on the agriculture — harvest whatever can be harvested and prepare for more rainfall,” President Miguel Díaz-Canel said in a meeting with government officials Tuesday.