"Tropical storm force winds are expected to move out of the area late Monday night".
Irma was about 105 miles (170 kilometres) northwest of Tampa, with maximum sustained winds of 70 miles per hour (110 kilometres per hour).
Late Sunday, as the storm moved up Florida's west coast, officials said 28,000 people had taken refuge in 45 county shelters in Hillsborough County, which includes Tampa.
Television footage showed trees down and buildings with exterior damage, though people were able to make their way through muddy or lightly flooded streets. But there are fears Fort Myers and Tampa are unprepared for the "dangerous" and "life-threatening" effects of the storm, which is expected to inundate Florida Keys with a surge of up to three metres.
Florida has already spent $77 million ahead of Irma's arrival.
Hurricane Irma remains a very large storm, almost three times the size of the state of Florida, and meteorologists are now predicting it will make a northwest turn sometime this weekend. Official National Hurricane Center track has Irma starting its track northward and strengthening slightly before making landfall along the west coast of Florida.
Some businesses are suspending their operations and closing early on Monday.
Baker, Ben Hill, Calhoun, Clay, Decatur, Early, Gadsden, Irwin, Lee, Liberty, Miller, Quitman, Randolph, Seminole, Terrell and Turner Counties in North Florida and South Georgia.
A tropical storm warning extends from central Georgia into northern Georgia and northwestern Alabama, including the cities of Atlanta, Georgia, and Huntsville, Alabama. A storm surge of 10 feet was recorded in the Keys and a record storm surge was reported in Jacksonville that exceeded the previous high set by Hurricane Dora in 1964.
"South Florida is already experiencing tropical storm force winds and risky seas", Scott said.
About 6.5 million Floridians were under mandatory or voluntary evacuations, the Florida Division of Emergency Management said Sunday.
The Florida Department of Transportation on Saturday started to close turnpike service plazas in South Florida, with the Fort Pierce and Fort Drum plazas shutting down Saturday night. We're still getting reports on that.
Miami and Miami Beach imposed the county's first curfews Saturday after Gimenez's own evacuation order for more than 600,000 residents left entire neighborhoods empty. It should slowly weaken as it interacts with land.
"Additional weakening is forecast, and Irma is expected to weaken to a tropical storm this morning and to a tropical depression by Tuesday afternoon", the Hurricane Center said. At least five people died of storm-related injuries in Florida as the massive hurricane barreled across the Sunshine State. He said he was expecting the worst to hit around 1 a.m. Monday. Petersburg area were braced for its first direct hit from a major hurricane since 1921.
"I know we're ready and I know we're responding to both hurricanes at the same time", Duke said at FEMA headquarters.