Authorities in Florida have urged residents to “make their preparations” as Tropical Storm Ian strengthened into a Category 1 hurricane early on Monday.
Ian was forecast to move northwest through the Caribbean, near Cuba and the Cayman Islands, and reach the state’s west coast by Wednesday.
The hurricane’s exact path is uncertain but Governor Ron DeSantis warned of “broad impacts throughout the state”.
Residents have been seen stocking up on food, water, medicine and fuel.
The National Hurricane Center (NHC) said it expects “rapid strengthening” from Ian over the next 48 hours, with maximum sustained winds of 75mph (121kmph).
An NHC official said Cuba could experience “extreme hurricane force winds, life threatening storm surge and heavy rainfall” later on Monday.
Classes have been cancelled in parts of the island, and evacuations have been planned in a handful of western provinces, including near the country’s tobacco region.
Authorities in the Cayman Islands, a British territory, are working to provide plywood, sandbags and other supplies to local residents,
“We must prepare for the worst and absolutely pray and hope for the best,” Premier Wayne Panton said in a video on Sunday.