"The storm is powerful and deadly," Scott said. "Do not ignore evacuation orders.
"Remember, we can rebuild your home, we can't rebuild your life," he said. "All Floridians should be prepared to evacuate soon."
Irma was downgraded overnight from a Category Five to a Category Four storm but it is still considered extremely dangerous, packing winds of 240 kilometers per hour.
"Today is the day to do the right thing for your family and get inland for safety," he said, adding that the storm "is wider than our entire state."
"It is expected to cause major and life threatening impacts from coast to coast," Scott said.