MIAMI, July 7 (UPI) -- Hurricane Dennis was continuing to strengthen Thursday night as it approached Cuba, the National Hurricane Center in Miami said.
At 8 p.m. EDT Dennis' center was about 135 miles west-southwest of Guantanamo. Hurricane Dennis was moving at 15 mph with winds of up to 130 mph.
Meanwhile, hurricane warnings have been issued for parts of the Florida Keys.
The Hurricane Warning Center said Dennis will be "very near the southern coast of central Cuba on Friday."
The warnings were issued for the lower Florida Keys from the Seven Mile Bridge westward to the Dry Tortugas. A tropical storm warning has been issued for the rest of the keys east of the Seven Mile Bridge to Ocean Reef and Florida Bay.
A hurricane watch remains in effect for much of Cuba, including the U.S. Naval Base and detention center at Guantanamo Bay.
A hurricane watch was issued for some of Cuba's provinces, including Isle of Youth, Pinar del Rio, La Habana, Ciudad de la Habana and Holguin.