Hurricane Blanca formed off Mexico's Pacific coast on Tuesday and was on track to strike the Los Cabos resorts during weekend elections, a year after major storm damage, forecasters said.

The tropical storm grew into a category one hurricane with maximum sustained winds of 120 kilometers (75 miles) per hour, said public safety coordinator Luis Felipe Puente.

Blanca was located some 605 kilometers (375 miles) southwest of Zihuatanejo, Guerrero state.

The US National Hurricane Center's five-day tracking map shows Blanca striking the southern tip of Baja California peninsula as a tropical storm on Sunday, when Mexican head to the polls in midterm elections.

"Rapid strengthening is forecast, and Blanca is forecast to become a major hurricane on Wednesday," the center said in its latest bulletin.

The hurricane was stationary at 2100 GMT and little motion was expected through Wednesday night, the Miami-based center said.

Blanca became the second hurricane of the Pacific season after Andres, which had reached Monday category four strength on the five-level Saffir-Simpson scale far off the coast.

Hurricane Odile ravaged Los Cabos in September 2014, causing millions of dollars in damages and killing six people.