FLORIDA - Hurricane Irma's winds have slowed slightly while it rakes Cuba, but the massive storm is expected to strengthen again as it approaches Florida. 

The U.S. National Hurricane Center in Miami said Saturday morning that Irma became a Category 3 storm with maximum sustained winds of 125 mph. Forecasters expect the storm to pick strength back up as it moves away from Cuba. 

The storm's center was about 175 miles southeast of Key West, Florida, as of 11 a.m. 

Meteorologists say damaging winds from Irma's outer bands were already arriving in South Florida. The storm was expected to reach the Florida Keys on Sunday morning before moving up the state's Gulf Coast.

Florida's governor is issuing urgent warnings to a third of his state's residents to evacuate ahead of a massive hurricane on track to be the state's most catastrophic ever. 

Gov. Rick Scott says the entire west coast of Florida will likely see dangerous affects from storm surge as Hurricane Irma comes ashore Sunday. About 6.3 million of the state's approximately 21 million residents have been asked to evacuate. 

During a Saturday news conference, he told those in evacuation zones: "You need to leave -- not tonight, not in an hour, right now" 

Scott said that the storm surge is expected to be up to 15 feet in some areas along the west coast of Florida. In the Tampa Bay area, Scott said the storm surge could be between 5 feet and 8 feet.

Scott said: "This is the most catastrophic storm the state has ever seen."