A Category 1 hurricane packs winds between 74 miles per hour and 95 miles per hour, as gauged by the scale.
Expected to be even more risky than the powerful winds are the storm surges that threaten Florida's coastal cities.
Several hurricane warnings and watches now are in effect for Florida and the Tampa Bay region, meaning that within the next two days, hurricane-force winds in excess of 74 miles per hour likely will be a reality.
"If Tampa stays on the east side of the eye, we expect the storm surge to be worse than if the eye moves inland and the west side of the storm hits it", he said.
The massive storm triggered evacuation orders for 5.6 million people before it made two landfalls in the state Sunday.
The flooding in Jacksonville was expected, at least to a point. The hashtag "Recover813" is being utilized on social media to help officials see the scale of damage caused by the storm.
Irma leaves two thirds of Florida without power
Close to 600,000 homes and businesses were without power as of Sunday morning, according to utilities. The biggest storm surge impact is expected at high tide around midday Monday, forecasters say.
After battering its way up Florida's Gulf Coast and downgraded to a Category 1, Hurricane Irma was expected to cross into Georgia on Monday afternoon as a tropical storm, leaving potentially risky storm surges in its wake.
The storm had carved a path of destruction through the Caribbean last week, where it was blamed for at least 27 deaths. Another death was reported from a auto crash near Orlando.
Some areas are still flooded in Naples, in southwestern Florida. The prime minister called the island "barely habitable".
The Republican president also issued a disaster declaration for Puerto Rico on Sunday and expanded federal funds available to the U.S. Virgin Islands in the aftermath of Irma, the White House said.
Florida Power & Light has projected that more than 80 percent of its 10 million customers across Florida -- 4.1 million of its 5 million customer accounts -- may experience power outages as the storm crosses the state.
The U.S. Virgin Islands are facing a potential humanitarian crisis, reports the New York Times U.S. military helicopters are dropping food and water aid, and almost 5,000 American troops are headed to the islands to help with relief efforts.