Hurricane Paula weakened further early on Thursday as it approached western Cuba on a path toward the country's tobacco-growing region and eventually Havana, but could bring heavy rains.
The US National Hurricane Center said maximum sustained winds of the Category 1 storm -- the lowest on the five-step Saffir-Simpson intensity scale -- had dropped to 75 miles per hour (120 kph). Paula was described as a small hurricane.
Its center was 30 miles (45 km) west of Cuba's westernmost province, Pinar del Rio, where landfall was expected on Thursday as the storm moved northeast, the Miami-based center said in its latest advisory.
"Weakening is expected during the next day or two as the center moves over Cuba and encounters unfavorable upper-level winds, and Paula is forecast to become a tropical storm later today (Thursday)," it said.
A tropical storm has winds between 39 and 73 mph (63 to 117 kph).
The hurricane center said Paula is expected to produce total rain accumulations of 3 to 6 inches (7.5 to 15 cm) with up to 10 inches (25 cm) possible in parts of western and central Cuba. In mountainous areas, the rain could cause life-threatening flash floods and mudslides, it said.
A tropical storm watch also was issued for part of the Florida Keys, 90 miles (145 km) north of Cuba.
Local officials in Cuba said freshly planted fields of Pinar del Rio's prized tobacco, from which world-famous Cuban cigars are made, had been protected and leaves from the previous harvest safely stored.
Paula, the 16th named storm of the busy 2010 Atlantic season and the ninth hurricane, grazed Mexico's Yucatan Peninsula on Wednesday but inflicted little damage to the tourist resorts on the country's Caribbean coast.
The hurricane did not affect any of Mexico's main offshore oil-producing regions in the Gulf of Mexico and was not expected to move into the U.S. oil and gas fields in the Gulf.