With Irma now lashing the state's south-west with sustained winds of 177km/h, and threatening tornadoes and a deadly storm surge on the east coast, weather forecasters have begun to notice a serious problem in how Americans are interpreting the cone.
As more than 1 million Floridians are under orders to evacuate, ABC News spoke to some Miami residents who are hunkering down at home as Hurricane Irma - the most powerful Atlantic storm in a decade - approaches.
In one of the largest US evacuations, almost 7 million people in the Southeast were warned to seek shelter, including 6.4 million in Florida alone.
Over 7.4 million homes and businesses were without power in Florida, Georgia, South Carolina and Alabama because of Hurricane Irma, according to state officials and utilities on Monday.
"All of us at FPL are now making final preparations for the landfall of Hurricane Irma", said FPL officials.
"When that sun came out this morning and the damage was minimal, it became a good day", said Tampa Mayor Bob Buckhorn. No injuries have been reported.
Almost 4.5 million homes and businesses across Florida lost power, and utility officials said it will take weeks to restore electricity to everyone.
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About 310,000 of Tampa Electric's 700,000 customers were estimated to have lost power in the wake of Irma, president and CEO Gordon Gillette told CNBC Monday. "You won't make it turn around (and) it will have very unsafe side effects". Two cranes have collapsed in high winds in the city.
"Everything is flooded", he said.
A tropical storm warning is in effect for much of northern and central parts of the state. "But I'm also very concerned about the storm surge".
Those who did not evacuate ahead of the storm are in danger, Federal Emergency Management Agency Administrator Brock Long said Saturday.
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. It will continue on its north-northwest track at 17 miles per hour towards Alabama.
South Carolina Gov. Henry McMaster issued a mandatory evacuation for some barrier islands. But by the time it struck in the middle of the night Monday, its winds were down to 100 miles per hour or less. The governor also ordered that the state government be shut Monday and Tuesday "for all employees except essential personnel".
Irma hit Cuba's Ciego de Avila province late Friday as a Category 5 hurricane before it weakened and headed to the United States. Irma made landfall on Marco Island off Florida's west coast at 15:35 local time (19:35 GMT) on Sunday, with winds of up to 120mph.