Florida's governor is warning residents that storm surge of up to 12 feet in places will inundate houses.
Gov. Rick Scott urged anyone living in an evacuation zone in southwest Florida to leave by noon Saturday as the threat of Hurricane Irma has shifted west.
He says the storm is ``going to go faster than you are.''
Scott said 25,000 people in Florida have already lost electricity as Irma's outer bands have begun hitting the southern part of the state.
The governor also warned of dangerous storm surge of between 6 feet (2 metres) and 12 feet (4 metres) across parts of Florida.
He said: ``This will cover your house.''
The National Hurricane Center says the eye of powerful Hurricane Irma is expected to hit southwest Florida and Tampa sometime Sunday, but the entire state will feel the storm's effects.
Hurricane Center spokesman and meteorologist Dennis Feltgen said Saturday that while Miami won't get the core of Irma it will still get life-threatening hurricane conditions.
The Category 4 storm pounded Cuba early Saturday with maximum sustained winds of 130 mph (215 kph). It was expected to strengthen before hitting Florida.