Anxious meteorologists said it had the potential of becoming one of the worst storms in the history of Florida's Panhandle.
The speed of the storm barreling toward the Florida Panhandle - Michael was moving north-northwest at 12 miles per hour (19 kph) - was among the hazards worrying forecasters at the National Hurricane Center on Tuesday morning. Cedar Key to Chassahowitzka could see storm surge topping out between 4 feet to 6 feet.
Michael is a Category 2 storm, with sustained wind speeds of nearly 100 miles per hour (155 km/h), according to NOAA.
On the exposed coast of Florida's Big Bend, most of the waterfront homes in Keaton Beach stood vacant amid fears of a life-threatening storm surge in an area that hadn't seen a potentially catastrophic major hurricane in decades. "You have rain, you have wind - but storm surge, that's a lot of water that can come onshore", said David Peaton, the assistant director of emergency management in Levy County, in an interview with local station WUFT.
The National Weather Service calls for highs in the upper 80s for the rest of the week, with lows in the 70s.
Petro says the problems with Michael will be compounded since the storm is coming just weeks after Hurricane Florence.
The storm is expected to make landfall on Wednesday.
Wakulla County issued a dire warning, saying it won't open any of its shelters - because they're safety-rated only for storms up to Category 2 strength, WFSU reports.
North Carolina is expected to feel impacts from Michael late Wednesday or early Thursday.
A hurricane warning was in effect for a more than 300-mile (480-km) stretch of coastline from the Florida-Alabama border to the Suwannee River in Florida.
Strong surf is impacting beaches in Gulf Shores, Ala. ahead of Hurricane Michael. Flooding rains of 10 to 20 centimetres, with hurricane force winds and storm surge of up to 3½ metres are in the forecast for the region.
It would head off the Mid-Atlantic coast by Friday, the NHC said.
The storm has become unsafe, with forecasters predicting life-threatening storm surge that will likely be exacerbated by the astronomical king tides. Florida Panhandle and Big Bend, southeast Alabama, and portions of southwest and central Georgia...4 to 8 inches, with isolated maximum amounts of 12 inches. Forecasters warned of up to 30cm of rain in western Cuba, triggering flash floods and mudslides in mountain areas, and disaster agencies in El Salvador, Honduras and Nicaragua reported 13 deaths as roofs collapsed and residents were carried away by swollen rivers. These swells are likely to cause life-threatening surf and rip current conditions. TORNADOES: The threat for tornadoes will increase late tonight into Wednesday over parts of the Florida Panhandle, the northern Florida Peninsula, and southern Georgia. Next complete advisory at 400 AM CDT.