In areas such as Playa del Carmen, on Mexico's popular Mayan Riviera holiday strip, tourists have been forced to huddle in shelters.
At one hotel, serving as a shelter for 400 people, as many as 12 people were sharing some rooms.
Saffir-Simpson Hurricane scale
Category 1 - Winds 119-153kph
Minor coastal flooding and structural damage
Category 2 – Winds 154-177kph
Damage to roofs, mobile homes and shanty houses. Some trees uprooted. Small boats may break moorings
Category 3 – Winds 178-209kph
Damage to buildings, mobile homes destroyed. Severe flooding near to coast
Category 4 – Winds 210-249kph
Major structural damage, roofs destroyed. Storm surge around 5m requiring widespread evacuation of coastal areas
Category 5 – Winds 249kph or higher
Serious damage to all but strongest buildings. Severe flooding far inland, all trees blown down. Storm surge up to 6m above normal
Emanuela Beriola, 41, an Italian tourist, said: "We could be two or three days without water or electricity."
He has stockpiled tinned meat, energy drinks and cans of tuna fish.
Christian Muller, a German engineer who is on holiday in the area, said: "I'm not scared. I telephoned my daughter and my mother and they are more worried than me."
Felipe Calderon, the Mexican president, says he is cutting short a trip to Canada to return home to oversee the response to the storm.
Al Jazeera's Rob Reynolds, who is near the town of Tulum on the Yucatan peninsula, said: "The wind is quite strong and we ares still some distance from the centre of the storm.
"The emergency services have put police and military personnel on the streets and opened a lot of shelters."
Mexico's state-owned Pemex oil company abandoned its offshore oil rigs off the coast of Yucatan, evacuating more than 14,000 workers and shutting down production in its main oil-producing region.
Pemex warned that temporarily closing its 407 undersea wells would mean a production loss of 2.7m barrels of oil and 2.6bn cubic feet of natural gas a day.
Residents of Belize, south of Mexico, are also bracing for the brunt of the storm's power.
Authorities have evacuated 6,000 people from the country's main tourist resort, San Pedro on Ambergris Caye, and another 500 or so from nearby Caye Caulker, said Jan Mohammed, the national emergency coordinator.
Belize City's three hospitals have moved high-risk patients to the inland capital, Belmopan, founded after 1961's Hurricane Hattie devastated Belize City.