TAMPA, Florida (REUTERS) - Hermine gathered strength to reach hurricane status on Thursday (Sept 1) as residents of Florida's northern Gulf Coast scrambled for sandbags, stocked up on food and evacuated low-lying areas ahead of what their governor called "a life-threatening storm."
Hermine is expected to be the first hurricane to strike the state in more than a decade.
The National Hurricane Centre said it became the fourth hurricane of the 2016 season around midafternoon when its sustained winds reached 120kmh while about 180km south-southwest of Apalachicola, Florida.
It was expected to make landfall late on Thursday or early on Friday.
Hermine was expected to dump as much as 51cm of rain in some parts of the state. Isolated tornadoes and storm surges as high as 2.45m were also forecast.
"Those on higher ground are stocking up and hunkering down,"said Pamela Brownlee, director of emergency management for coastal Franklin County.
She said people on barrier islands and low-lying areas on the shore are being evacuated.
Governor Rick Scott declared a state of emergency in 51 of Florida's 67 counties in advance of the storm.
Mandatory evacuations were ordered in parts of five counties in northwestern Florida, including Franklin, and voluntary evacuations were in place in three more coastal counties, Scott told reporters.
"This is a deadly, life-threatening storm," Scott said, noting that 8,000 members of the Florida National Guard were prepared to be mobilised.
The last hurricane to strike Florida was Wilma in 2005, the hurricane centre said.
Towns, cities and counties along the Gulf Coast have been hastily preparing shelters for people and pets, setting up centers where residents could fill sandbags for personal use and placing electric line repair crews on standby ahead of the storm.
Water spilling from rough seas already was inundating roads in some waterfront communities in the Tampa Bay region.
Tony Crowley, 53, was unable to drive his car through more than a metre of water in coastal Gulfport, so he parked blocks away and walked barefoot with his dog, Izzy, between downpours. "I love storms so long as they aren't damaging," he said.
After battering coastal Florida, Hermine is expected to barrel across the northern part of the state into Georgia, then slam southern US coastal regions on the Atlantic. Tropical storm warnings have been issued through parts of North Carolina.
Many schools from Florida's central Gulf Coast to Tallahassee were closed on Thursday.
On its current path, the storm also could dump as much as 25cm of rain on coastal areas of Georgia, which was under a tropical storm watch, and the Carolinas. Flash flood watches extended from Florida into Virginia.
Georgia Governor Nathan Deal on Thursday signed an executive order declaring a state of emergency for 56 counties that runs through midnight on Saturday.
Some US oil and gas producers in the eastern parts of the Gulf of Mexico were returning workers to offshore facilities on Thursday and restarting operations shut as the system moved toward Florida.
In the Pacific, a hurricane watch was issued for Hawaii and Maui counties as Hurricane Lester, currently a Category 2 storm, approaches the state. While expected to continue weakening, it could affect Hawaii during the weekend.