Thousands of tourists and locals are fleeing the Mexican coast ahead of the arrival of the category four Hurricane Wilma.
"The most important thing now is to protect lives, protect the lives of our children, of our grandparents," Mexican President Vicente Fox said in a broadcast address to the nation.
After the airport at Cancun was closed, tourists shuttled from luxury hotels to emergency shelters ahead of Wilma, which forecasters said was growing stronger. Cuba evacuated more than 200,000 people as the storm approached.
Cuba has evacuated more than 200,000 people from its expected path across western Cuba and five cities along the Mexican coast have declared a state of emergency and set up hundreds of emergency shelters.
Belize and Honduras are also on tropical storm watch.
Wilma, a Category 4 storm with winds of 150 mph, has already killed at least 13 people.
For a while the most intense Atlantic hurricane on record, Wilma weakened from a Category 5 storm. Its 150 mph winds made it more powerful than Hurricane Katrina when it hit the Gulf coast of the United States in August, killing more than 1,200 people.
Forecasters have predicted Wilma would swing northeast around Cuba to hit Florida by Sunday. Governor Jeb Bush has declared a state of emergency in the State.
The hurricane's eye is so large it might take hours to pass over land, leading to fears that confused residents might leave shelters in the middle of the storm.
"The eye is very large, 65 kilometers across, and in those six or seven hours of apparent calm, people might get confused," said Quintana Roo Gov. Felix Gonzalez Cantu, whose state includes Cancun.
The slow-moving hurricane, which was heading northwest at about 6 mph, was expected to churn over land for almost a full day.
At the beachside Playa Azul hotel on Cozumel's north end, manager Martha Nieto said "the waves are getting very high." "We wish it would be over. The waiting drives you to desperation," Nieto said by telephone.