The U.S. National Hurricane Center said early Saturday that Hurricane Isaias is getting "a little stronger" as it drenches the Bahamas and makes its way toward the U.S. mainland.
Isaias is moving northwest with maximum sustained winds at 135 kph, according to meteorologists.
Isaias, located about 185 kilometers south southeast of Nassau, is expected to make landfall on Florida's southeastern coast late Saturday or Sunday.
The southern U.S. states of Florida and North Carolina have declared hurricane warnings.
Florida Gov. Ron DeSantis has declared a state of emergency for a dozen counties on the Atlantic Coast. Heavy rains from the storm are expected to begin in Florida on Saturday and arrive over the Carolinas by early next week.
In North Carolina, Gov. Roy Cooper also declared emergencies in coastal counties and ordered the evacuation of Oracoke Island, which was hit by last year's Hurricane Dorian.
The hurricane has prompted authorities in parts of Florida to close coronavirus testing sites at a time when cases have been growing in the state.
Officials in Miami-Dade County said they do not believe it will be necessary to open evacuation centers for this storm but said 20 centers remain on standby in case conditions change.
In the Bahamas, officials evacuated people in Abaco and in the eastern end of Grand Bahama who have been living in temporary structures since Hurricane Dorian.
Earlier, while still a tropical storm, Isaias lashed Puerto Rico and the Dominican Republic, causing power outages and small landslides.
A man died in the Dominican Republic when he was electrocuted by a fallen electrical cable, according to the Associated Press.
U.S. President Donald Trump has signed an emergency declaration for Puerto Rico, which has yet to fully recover from 2017's Hurricane Maria and a recent series of earthquakes.
Isaias is the ninth named storm of a busy Atlantic hurricane season. This is the earliest date a storm beginning with the letter "I" has formed.