Tropical Storm Hermine has strengthened into a hurricane as it heads towards Florida, forecasters have said.
The US National Hurricane Center said Hermine is located about 185km south-southwest of Apalachicola, Florida, carrying winds of 120km per hour.
It's feared the hurricane, the fourth of the 2016 Atlantic season, could eventually pack wind speeds of up to 150km per hour.
"The centre of Hermine will be near the Florida coast in the warning area tonight or early Friday," the forecasters said.
Alerts have been issued as the storm approaches from the Gulf of Mexico.
The Florida governor Rick Scott has warned the hurricane is potentially life-threatening and is urging Gulf Coast residents to take precautions immediately.
Storm surges, flooding, fallen trees and power outages are expected.
The warning covers an area from Marineland in Florida to South Santee River in South Carolina.
A hurricane warning was already in effect for a section of Florida's Gulf coast from the Suwanne River to Mexico Beach, and tropical storm warnings in effect for other sections of the coastline.
