Tropical Storm Idalia is expected to intensify into a major hurricane today as it barrels toward Florida's Gulf Coast.
Authorities have urged millions of residents to prepare to evacuate ahead of an expected landfall early Wednesday morning.
Idalia, with maximum sustained winds of 105kmph, was churning in the Caribbean today, about 144km off Western Cuba, the National Hurricane Center said in an advisory.
The storm's growing intensity and its current northerly track put some 20 million people in the US state under hurricane and tropical storm watches.
Idalia is predicted to be Category 3 on the Saffir-Simpson Hurricane Wind Scale when it makes landfall in northern Florida's Big Bend area, the hurricane centre said.
"All Floridians, you need to be executing your plans," Florida Governor Ron DeSantis said during a news conference today.
"This is going to be a major hurricane. This is going to be a powerful hurricane and this is absolutely going to impact the state of Florida."
Local officials along the state's Gulf Coast were preparing to issue evacuation orders today, Mr DeSantis said, noting that people in the area should prepare to lose power.
"Keep in mind, if you are told to evacuate, you do not need to drive hundreds of miles, you do not need to leave the state of Florida.
"You basically need to go to higher ground," he said, adding that many school districts were also planning to cancel classes.
By tomorrow, Florida's Gulf Coast, southeast Georgia and the eastern North and South Carolina should expect torrential rains of 10cm to 20cm that could cause scattered flash and urban flooding to begin.
Along with the heavy rain, winds of more than 177km/h per hour could result in life-threatening storm surge, the centre warned.
Like many beachfront communities along the coast, the city of Bradenton opened sandbag stations and urged its 55,000 residents to stay vigilant.
"Let's be prepared - secure items that could become airborne, gas up your car, have cash and bottled water on hand," it said in a post on the social media platform X, formerly known as Twitter.
Emergency Shelters
In other communities, such as Hillsborough County, officials declared an emergency and set up shelters where those in need can ride out the storm.
Mr DeSantis issued a state of emergency for 46 Florida counties covering most of the northern part of the state.
Some 5,500 members of the National Guard were mobilised, with 2,400 high-water vehicles and a dozen aircraft deployed for rescue and recovery efforts.
Along with thousands of electric workers staged to help restore power quickly after the storm passes, the state has about 11.3 million litres of drinking water and 1.5 million meals ready to hand out to people in need after the storm, Mr DeSantis said.
Duke Energy, which serves many parts of the state's northwestern area, said it was preparing crews and equipment to respond to the storm if customers lose power.
To the east of Idalia, Hurricane Franklin, the first major hurricane of the season, meandered in the Atlantic, where it was forecast to turn to the northeast over the next two days.
The Category 3 hurricane threatened to heavy swells to Bermuda and the US East Coast throughout the week.
