The Mexican state of Veracruz was hit by torrential rains during the early afternoon on Thursday after Tropical Storm Barry made landfall and traveled inland, away from Mexico's major oil installations.
Two of Mexico's three major oil-exporting ports - Dos Bocas and Cayo Arcas - remained closed, but state oil monopoly Pemex said it was unaffected by the storm.
Almost all of Mexico's crude oil exports, which totaled 1.275 million barrels per day in April, are shipped to refineries on the Gulf Coast of the United States from the ports of Coatzacoalcos, Dos Bocas and Cayo Arcas.
The rains falling in the town of Actopan in Veracruz were more severe than those during Hurricane Karl, a category 3 storm that battered the state in 2010, town spokesman Rafael Alberto Moreno said.
There is a risk that the Actopan river, one of the biggest in the state, might overflow and townspeople were being evacuated from their homes, he said.
Barry is expected to lose strength as it moves west across land, and the tropical storm warning will probably be discontinued Thursday afternoon, the U.S. National Hurricane Center said in an advisory.
Veracruz is home to the Minatitlan refinery, Pemex's fifth-largest and the most recently modernized. It has the capacity to produce 245,000 barrels per day.
Pemex also has three petrochemical complexes and three gas processing complexes in Veracruz.
Asked about the state of Pemex's installations in the Gulf of Mexico, a company official texted: "Everything is OK."
Maximum sustained winds had decreased to 40 miles per hour (64 km/h).
The National Hurricane Center said it expected 3 to 5 inches (7.6 to 12.7 cm) of rainfall, with maximum accumulations of 10 inches (25 cm) over portions of southern Mexico. Tropical storm winds will probably continue for several hours and subside later Thursday, the center said.