The storm is expected to strengthen as it moves through the warmer waters of the Gulf of Mexico.
If Michael continues to intensify and stay on the National Hurricane Center's forecasted path, storm surge impacts east of the hurricane's eye are expected to be most severe, where storm surge and waves could bring water levels to rise as high as 16 to 20 feet, the USGS predicts.
In the small Panhandle city of Apalachicola, Mayor Van Johnson Sr said the 2300 residents were frantically preparing for what could be a strike unlike any seen there in decades. The governor has also warned that there is a "significant" chance of tornadoes.
"Don't think that you can ride this out if you're in a low-lying area", Nelson said on CNN.
As Michael moved over open water, energy companies halted almost one-fifth of Gulf of Mexico oil production and evacuated personnel from 10 platforms on Monday.
The Gulf of Mexico is home to 17 per cent of daily US crude oil output and 5 per cent of daily natural gas output, according to the US Energy Information Administration.
The advisories for Hurricane Michael as of October 9, 2018.
Hurricane Warnings are in effect from the Alabama-Florida border to the Suwannee River, and a Tropical Storm Warning is in effect for Florida's west coast from the Suwannee River to Chassahowitzka.
"I've spoken to FEMA administrator Brock long several times - a team from FEMA is here at the state's emergency operation center and providing federal assistance, " announced Scott.
Some 1,250 National Guard soldiers are helping residents in coastal areas to find safety, and another 4,000 are on standby, Mr Scott said.
With just a month to go before Election Day, Florida voters in evacuation zones were given an extra day to register to vote, once offices reopen after the storm.
In Florida, state offices, schools and universities were set to close on Tuesday through the end of the week in panhandle counties. Lines at gasoline stations were growing as people prepared to leave. Because he owns two businesses in the area, Givens, who lives inland, said he was not evacuating.
Coastal residents rushed to board up their homes and stock up on bottled water and other supplies.
Panama City's Bay County and other counties used their social media channels to alert residents about shelter openings.
The National Hurricane center says the storm is expected to become a major hurricane by Tuesday night.
Torrential downpours and flash flooding from the storm over the weekend caused 13 deaths in Central America.
The 11 a.m. advisory for Hurricane Michael shows it is up to a 110-mph Category 2 hurricane - one mile below a Category 3. By Friday (Oct. 12), the storm will make its way out over the northern Atlantic, NOAA is now predicting.
Wednesday: Showers and thunderstorms are possible from the outer rain bands of Michael or its remnants.
If it makes landfall as a Category 3 it will be the first major hurricane to hit the Panhandle since Hurricane Dennis came ashore near Pensacola on July 10, 2005 with 130 miles per hour winds. It would head off the Mid-Atlantic coast by Friday, the NHC said.
In Georgia, Gov. Nathan Deal declared an emergency for 92 counties. Heavy rain could trigger the same kind of unsafe flash flooding in the Big Bend, Panhandle, Georgia and SC, forecasters warned.