Florida Gov. Charlie Crist issued a state of emergency in what is considered a precautionary measure as tropical storm Hanna looms.
Florida should be ready for flash floods and winds up to 175 km/h if the storm hits in the coming days, Crist said Tuesday.
However, there is no certainty Hanna will hit Florida. Current forecasts show it could also make landfall in coastal Georgia, the Carolinas or elsewhere.
Crist's emergency declaration allows the state to more easily mobilize employees, law enforcement personnel and other resources.
Hanna was classified a hurricane Monday, but had weakened back to a tropical storm Tuesday.
At 8 p.m. ET Wednesday, Hanna's maximum sustained winds were near 105 km/h, but the U.S. National Hurricane Center in Miami said it could regain hurricane strength as it turns towards the east coast of the United States in the next few days.
Forecasters predicted the centre of Hanna could move over central and northwestern Bahamas as soon as Wednesday.
Hanna, who on Wednesday night was 20 kilometres east-southeast of San Salvador in the Bahamas and 630 kilometres east-southeast of Nassau, is the third storm to threaten Florida in three weeks.
Death toll in Haiti increases to 23
The storm has left a swath of death and destruction in Haiti, which is still recovering from drenchings by Hurricane Gustav and tropical storm Fay in the past two weeks.
In all, floods and mudslides from the three storms have killed more than 100 people as Haiti's deforested hills melted away in torrential rains.
Haitian authorities on Wednesday reported two more deaths caused by Hanna, raising the toll to 23.
Floodwaters swamped a hospital in the Les Cayes area, forcing nurses to move patients to higher floors. At least 5,000 people in Les Cayes remained in shelters, said Jean-Renand Valiere, a co-ordinator for the civil protection department.
High water still prevented UN soldiers from reaching the western city of Gonaives, where the rise of muddy water drove people to seek refuge on rooftops Tuesday as wind gusts drove horizontal sheets of rain.
Earlier Tuesday, another convoy carrying Prime Minister Michele Pierre-Louis had to abandon efforts at getting into Gonaives when one of the cars was nearly swept away, said Julian Frantz, a Haitian police officer who was providing security for the group.
"The situation is as bad as it can be," said Vadre Louis, a UN official in Gonaives on Tuesday.
"The wind is ripping up trees. Houses are flooded with water. Cars can't drive on the street. You can't rescue anyone, wherever they may be."
Those who could move clutched mattresses, chairs and other belongings as they slogged through waist-high floodwaters.
Elsewhere, Hurricane Ike grew into a Categry 3 hurricane with winds near 185 km/h Wednesday night. The hurricane is located far out in the Atlantic about 1,035 kilometres east-northeast of the Leeward Islands.