At 5 p.m. EDT (2100 GMT), Dean was located about 270 miles (435 km) east of Chetumal, Mexico.

Dean was moving west at 20 mph, with maximum sustained winds still near 150 mph, and was expected to hit the east coast of the Yucatan Peninsula late Monday evening or very early Tuesday morning.

The NHC said it was likely that Dean would strengthen to Category 5 status, the highest on the Saffir-Simpson scale, with winds of 156 mph or greater, before making landfall.

A westward or west-northwestward motion was expected to continue for the next 24 hours.

Computer models showed Dean crossing the YucataN on Tuesday, then moving into the Bay of Campeche in the southwest Gulf of Mexico before making landfall Wednesday afternoon in Mexico between Veracruz and Tampico.

While Dean was not expected to land anywhere near the refineries or key oil and gas producing platforms located along the Texas coast, it was already disrupting oil and gas operations in Mexico's Bay of Campeche.

Mexico's state oil company Pemex said Monday it will close all oil and gas wells in the main Campeche Sound region due to the storm, losing production of some 2.65 million barrels of crude per day, or over 80 percent of its total crude output.

The NHC said it expected Dean to weaken as it crossed the Yucatan but still retain hurricane status before it restrengthens in the Bay of Campeche.