The storm comes less than a fortnight after Hurricane Helene caused widespread damage and killed more than 200 people.
A hurricane set to hit the US has strengthened into a Category 5 storm – as Florida prepares for its largest evacuation in seven years.
Hurricane Milton is forecast to make landfall on Wednesday.
The weather system was upgraded by the National Hurricane Center after sustaining winds of 180mph (285kmh) while sweeping east across the Gulf of Mexico.
It’s predicted to hit around the Tampa Bay area before travelling over Orlando.
There’s a warning of a possible eight to 12-foot storm surge (2.4 to 3.6m) – the highest ever for the region – and the potential for widespread flooding.
“This is the real deal here with Milton,” Tampa mayor Jane Castor told the media. “If you want to take on Mother Nature, she wins 100% of the time.”
It comes after more than 200 people were killed when Hurricane Helene tore across the southeastern US, including parts of Florida, late last month. That was a Category 4 storm when it made landfall.
Forecasters say some affected areas will likely be hit again, worsening the damage caused less than a fortnight ago.
Kevin Guthrie, director of Florida’s emergency management division, warned that residents should prepare for the “largest evacuation that we have seen, most likely since 2017 Hurricane Irma”.
He added: “I highly encourage you to evacuate.”
Sheriff Chad Chronister said the situation “stinks” but “if you safeguard your families, you will be alive”.
The fire service warned there was a risk to life for anyone staying in the area.
“If you remain there, you could die and my men and women could die trying to rescue you,” fire service chief Jason Dougherty said. “Help them by leaving.”
In 2017, around seven million people were ordered to flee their homes in Florida ahead of Hurricane Irma, which ended up killing more than 130 people in the state.
The mass evacuation caused long traffic jams on motorways and major queues at petrol stations.
Officials say they have learnt lessons from the chaotic scenes in 2017, and will have emergency fuel stations and charging points for electric vehicles along evacuation routes.
Florida Governor Ron DeSantis warned power cuts were likely and that debris already caused by Hurricane Helene would be added to.
He added: “I don’t think there’s any scenario where we don’t have major impacts at this point.
“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.”
Pinellas County, which includes the city of St Petersburg, is likely to issue mandatory evacuations for more than 500,000 people in the lowest-lying areas on Monday, officials told a news conference.
Evacuations have already been ordered for six hospitals, 25 nursing homes and 44 assisted living facilities in the county.