In its 11 p.m. EDT advisory, the National Hurricane Center in Miami said the Category 1 hurricane was 40 miles east of Chetumal, Mexico and about 200 miles east-southeast of Campeche, Mexico.
Ernesto was spitting out 85 mph winds up to 35 miles from its center and tropical storm-force winds up to 175 miles out. It was headed westerly at 15 mph and was forecast to move across the peninsula Tuesday night and early Wednesday, emerging over the Bay of Campeche by Wednesday afternoon or evening.
Some weakening was expected as the big storm lumbers over land, the hurricane center said.
A hurricane warning was in place from Chetumal to Tulum on the east coast of the Yucatan Peninsula, Cozumel and the coast of Belize from Belize City northward to the Mexican border.
The Mexican government issued a hurricane watch for mainland Mexico from Barra de Nautla southward to Punta el Lagarto. A tropical storm watch was in effect from north of Barra de Nautla northward to Tuxpan, Mexico.
A tropical storm warning was in effect from north of Tulum to Cabo Catoche on the Yucatan Peninsula's east coast, as well as south of Belize City southward to the Guatemalan border and from Celestun southward and westward to Chilitepec along the Gulf Coast of Mexico.
A tropical storm watch was ordered for north of Barra de Nautla to Tuxpan, Mexico.