Florida authorities ordered gulf coast residents to head inland or get ready to evacuate as Hurricane Michael, predicted to strengthen rapidly, heads towards the US coast.
The storm is already lashing Cuba with strong winds and heavy rains.
It is currently a category 1 hurricane but may reach category 3 with winds over 160 km/h before it hits the US coast, possibly on Wednesday, making it one of the most powerful storms to hit the Panhandle of Florida in decades.
It is then forecast to move up the east coast. North Carolina may receive 2cm to 7cm of rain, officials say, which could trigger flash flooding due to the existing level of saturation in the ground from Hurricane Florence, which struck North and South Carolina last month.
The hurricane's current wind speeds are 120km/h.
Forecasters with the US National Hurricane Center in Miami say it is carrying winds of up to 130km/h and warn it will continue to move over warm waters, which may cause it to generate winds reaching 178km/h by Tuesday night.
Parts of Florida may receive up to 30cm of rain, leading to the possibility of severe flooding.
Florida Governor Rick Scott, who suspended his Republican campaign for the US Senate to deal with the approaching storm, issued a state of emergency for 26 counties of Florida on Sunday.
"This storm will be life-threatening and extremely dangerous," Gov Scott said after he received a briefing at the state's emergency management centre.
Mandatory evacuation orders were issued on Monday for residents in various areas in Florida's Gulf and Bay counties, according to a statement from county emergency officials. Mandatory evacuations were issued for all non-residents in Franklin County, home to various tourist attractions like St. George Island.
The city of Tallahassee has opened two locations for residents to pick up sandbags in anticipation of flooding.
"While the impacts are still uncertain, our area could experience increased wind activity and heavy rainfall, which could cause localised flooding and downed trees," Tallahassee officials said in a statement.
Tallahassee Democratic Mayor Andrew Gillum, who will face off against Gov Scott in the November election, has also suspended his campaign and returned to the northern Florida city to help with storm preparations.
Florida State University in Tallahassee announced it was shutting down its campus after midnight on Monday, and will remain closed for the rest of the week.
- BBC / Reuters