Based on wind speed, it was the fourth-strongest, behind the Labor Day storm (184 miles per hour, or 296 kph), Camille and Andrew in 1992.
Meanwhile, the state is expecting a surge in humanitarian needs, from a lack of food and water to housing.
Increasingly, climate change is part of the risky mix as well.
The National Hurricane Center (NHC) warned of possible flash flooding Thursday in parts of Georgia, the Carolinas and southeastern Virginia because of heavy rains from Michael. "It came out of nowhere and really intensified rapidly".
A Tropical Storm Warning is in effect for. "It had the pedal to the metal all the way until it hit the coast", he said.
Florida Governor Rick Scott told the Weather Channel the damage from Panama City down to Mexico Beach was "way worse than anybody ever anticipated".
Michael's barometric pressure at landfall was 919 millibars, by that measurement the third-strongest hurricane to hit the USA on record, trailing on the 1935 Labor Day Hurricane and Hurricane Camille in 1969.
The storm was on track to make an expected exit into the Atlantic Ocean by Friday morning, with some parts of Virginia and North Carolina expected to see as much as nine inches of rain, bringing the likelihood for risky flooding.
"The state is mobilizing all available resources to ensure public safety ahead of Hurricane Michael", Deal said.
The strengthening occurred despite pronounced wind shear in the region that might have been expected to weaken the storm, she added. Bill Nelson, said a "wall of water" could cause destruction along the Panhandle.
President Donald Trump told reporters on Tuesday: "We are very well prepared for the incoming hurricane".
Warm water is "basically the battery for, the fuel, that hurricanes feed off of", said Jennifer Francis, a professor of atmospheric sciences at Rutgers University's department of marine and coastal sciences. "On the forecast track, the center of Michael will move across the eastern Gulf of Mexico through tonight".
It is too early to say how much global warming contributed to Michael's ferocity.
It was the strongest to hit the continental United States since Hurricane Andrew in 1992.
At an election rally in Pennsylvania on Wednesday night, Trump offered his "thoughts and prayers" to those in the path of the storm and said he would visit Florida soon.
Even without the scientific calculations, he said, the connection makes intuitive sense. But without extensive study, they can not directly link a single weather event to the changing climate.
Many flights were canceled in the hurricane zone, and Amtrak changed some train schedules to protect passengers and employees.
Storm surge is also inundating some areas along the Panhandle.
Panama City could see a storm surge at depths from 6 to 9 feet. But it's still menacing the Southeast with heavy rains, winds and a threat of spinoff tornadoes.
Previous year saw a string of catastrophic storms batter the western Atlantic - including Irma, Maria and Harvey, which caused a record-equaling $125 billion in damage when it flooded the Houston metropolitan area.
Michael was located about 360 miles south of Panama City and was moving north at 12 mph.
By 8 a.m., winds had slowed to 50 mph as Michael crossed SC, about 40 miles west of Columbia, The storm had picked up speed to a fast 21 mph and should continue weakening.
While there is growing scientific agreement on numerous theories about the effects of climate change on storms, there are also areas where consensus has yet to develop.
An estimated 375,000 people in more than 20 counties were ordered or advised to evacuate.
Where has Hurricane Michael hit so far?
Brooks said he wasn't able to get out much overnight to fully assess the damage in the county, because downed power lines and trees made roads impassable in the darkness. "We've had a number of them come into the Gulf, and either come to the left or the right of us".
He drew an analogy to our wardrobes.