The storm was 440 miles (710 km) west-southwest of the port city of Manzanillo, the Miami-based National Hurricane Center said.
Jova was moving slowly - near 3 mph (5 kph) - toward the east-northeast. It is forecast to strengthen during the next 48 hours, with some forecast models calling for it to become a major hurricane before landfall in Mexico next week, the center said.
There were no coastal watches or warnings in effect and all of Mexico's major ports were open. Mexico has no oil installations in the Pacific.