Hurricane Michael became a Category 3 storm with 120 miles per hour maximum sustained winds on October 9-ahead of making landfall along the Florida Panhandle, according to the National Oceanic and Atmospheric Administration (NOAA).
Governor Scott warned in a news conference that Hurricane Michael is a "massive storm that could bring total devastation to parts of our state, especially in the panhandle".
Officials in Bay County say they have not seen a rush of evacuees clogging roads inland - and that worries them with just hours left before Michael's landfall in the Panhandle.
Bay County Sheriff Tommy Ford said he's "not seeing the level of traffic" he would expect when three-quarters of the county's residents are under mandatory and voluntary evacuation orders.
The storm then looks destined to move through the southeast USA on Thursday as a tropical storm, bringing heavy rains to Georgia and the Carolinas, before moving back out to the Atlantic on Friday. "We want to get them out of the way".
University of Georgia's Marshall Shepherd, a former president of the American Meteorological Society, called it a "life-altering event" on Facebook and said he watched the storm's growth on satellite images with a pit growing in his stomach. As a result, the northeastern Gulf Coast is undergoing mandatory evacuations - that includes the Florida Panhandle (stretching into Big Bend) as well as parts of southeast Alabama and southern Georgia.
A tropical storm warning was issued from Fernandina Beach Florida to South Santee River South Carolina.
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In the dangerously exposed coastal town of Apalachicola, population 2,500, Sally Crown planned to go home and hunker down with her two dogs.
Aja Kemp, 36, planned to stay in her mobile home in Crawfordville. "But in my experience, it's always blown way out of proportion".
The NOAA's National Hurricane Centre (NHC) forecasts Michael will become a Category 3 hurricane on the five-step Saffir-Simpson scale before coming ashore on Wednesday midday over the Panhandle or the Big Bend area.
Scott also told caregivers at north Florida hospitals and nursing homes to do all they can to assure the safety of the elderly and infirm.
As the storm closed in on the US, it caused havoc in the Caribbean.
With just a month to go before Election Day, Florida voters in evacuation zones also were given one more day to register to vote, once offices reopen after the storm.
Wednesday Governor Cooper declared a "State of Emergency" and announced he has activate the National Guard. Forecasters warned of up to a foot (30 centimeters) of rain in western Cuba, triggering flash floods and mudslides in mountain areas.
The weekend before Irma made landfall, Scott minced no words: "If you have been ordered to evacuate, you need to leave now", he said.