Irma is starting to spin up funnel clouds and at least one tornado, leading to warnings for parts of South Florida. The Weather Channel warned that wind gusts in Miami could reach 160 km/h. There was no immediate word on any damage or injuries.
But that soon changed.
CNN reported that Irma is expected to cross the lower Florida Keys on Sunday morning before pounding on the state's west coast by Sunday afternoon, where it threatened storm surge of up to 4.6meters, a height that is enough to cover a house.
The Miami metro area could still get pounded with life-threatening hurricane winds.
Tampa has not been struck by a major hurricane since 1921, when its population was about 10,000, National Hurricane Center spokesman Dennis Feltgen said. It has already left more than 20 people dead in its wake, not including Cuba, which has yet to survey damage.
The government also told all residents to stay inside and put the island and nearby St. Barts on its highest alert level as a new storm, Hurricane Jose, bears down on the area.
"We're as prepared as you can be for such an event, that I can say", Trump said during the Cabinet meeting at the Camp David presidential retreat in Maryland, according to video footage posted on Twitter.
With more than 6.5 million Floridians ordered to evacuate ahead of the storm, some of the approximately 29,000 who had taken refuge in county-run shelters - a record - started getting stir-crazy Saturday afternoon and made a decision to go back home, despite warnings that Irma had yet to arrive, and road conditions were deteriorating.
Irma's winds were down considerably from its peak of 185 miles per hour (300 kph) earlier in the week.
Hundreds of thousands of people are without power in Florida as Hurricane Irma's winds and rain lash the state.
Almost the entire Florida coastline remained under hurricane watches and warnings, and the latest projections could shift again, sparing or savaging other parts of the state.
Another 3.5 million are vulnerable to storm surge, which could reach 15 feet, inundating areas from Captiva to Cape Sable.
President Trump has warned people in Hurricane Irma's path "to get out of its way", as Florida braces itself for a storm of "enormous destructive power".
Graphics appeared online, suggesting how people could "fire correctly" at the hurricane to ensure the bullets did not come back and kill you. Many Florida families say online retailers let them down at the worst possible moment with cancellations and no-shows ahead of powerful Hurricane Irma even before the weather deteriorated.
At least half a million people already are without power in the state, and some 50,000 people are in shelters. Irma made landfall just after 9 a.m.at Cudjoe Key, about 20 miles outside Key West, forecasters said. Buildings collapsed, trees and power lines tumbled and roofs flew away in the 130-mile-an-hour winds. "I don't want that", he said. "Tonight, I'm scared to death".
The governor activated all 7,000 members of the Florida National Guard, and 30,000 guardsmen from elsewhere were on standby.
The live stream at Key West has proved a big hit online, and this is one of the reasons why. This is a vastly different city from the one that weathered Andrew in 1992.
Meanwhile, search-and-rescue teams located in Orlando and other staging areas were waiting out the storm until it was safe enough to go out and assess the extent of the damage and injuries. The agency, which is charged with controlling inland flooding, said Saturday it would no longer have to shut down the entire water flow system along canals, as it had feared.