Hurricane Wilma has strengthened to an extremely dangerous Category 5 storm as it approaches western Cuba and Mexico's Yucatan Peninsula.
The storm has already triggered mudslides that killed up to 10 people in Haiti.
The season's record-tying 21st storm in the region, fueled by the warm waters of the northwest Caribbean Sea, strengthened rapidly as it headed into the Gulf of Mexico on a path expected to lead across storm-weary southern Florida by Saturday.
A US Air Force plane has measured maximum sustained winds of near 240km from the vicious storm, America's hurricane centre reported at 7.30am Irish time today.
As of 6am Irish time, the center of the storm was about 280km south-southwest of Grand Cayman and about 655km southeast of Cozumel, Mexico, according to the centre's website.
A hurricane watch was in effect for the east coast of Mexico's Yucatan peninsula from Cabo Catoche to Punta Gruesa and for the provinces of Matanzas westward through Pinar del Rio in Cuba, the hurricane center reported.
Wilma is the 21st tropical cyclone of the Atlantic hurricane season, tying the record for most storms set in 1933. It was also the 12th hurricane and tied the record for most hurricanes in a season, set in 1969. The season still has six weeks to run.
The hurricane is not expected to threaten New Orleans or Mississippi, where Hurricane Katrina killed more than 1,200 people and caused more than $30 billion of insured damage in August.
Katrina was followed in September by Hurricane Rita. Wilma is also expected to miss the Gulf of Mexico oil and gas facilities that are still reeling from Katrina and Rita.
But frozen orange juice futures closed at a six-year high yesterday amid fears Wilma could ravage Florida groves that had just begun to rebound from the hurricanes that destroyed 40 per cent of last year's crop.
Wilma is expected to deluge the Caymans, Jamaica, Haiti, Cuba, Honduras and Nicaragua, with isolated rainfall amounts of up to 38 cm possible. Emergency crews in Honduras prepared to evacuate 10,000 people, including tourists drawn to the Bay Islands of Roatan, Utila and Guanaja to scuba dive the pristine coral reefs.
Cuba's western tobacco-growing province of Pinar del Rio braced for heavy rain and flooding. More than 5,000 people were evacuated from eastern Cuba, where two days of rainfall caused floods and mudslides in the provinces of Guantanamo, Santiago and Granma
The Florida Keys, a chain of islands connected to mainland Florida by a single road, planned to order visitors to leave tomorrow and to evacuate 80,000 residents on Friday.
"This is our fourth storm but this one is really aggressive. This one we are taking seriously. The damage is going to be substantial," Irene Toner, director of emergency management for the county that encompasses the islands, told local radio.