Six Mexican states are on high alert for Hurricane Marie, warning that torrential rain could trigger mudslides and cause rivers to break their banks.

Marie, the eighth hurricane of the eastern Pacific season, was packing maximum sustained winds of 85 miles (140km) per hour on Saturday and gaining strength, according to the Miami-based National Hurricane Center (NHC), which cautioned it will likely become a major hurricane by Sunday.

The storm was far from land – some 330 miles south-southwest of the Mexican port city of Manzanillo – and no storm watches or warnings were in effect for the coast.

However, the NHC said portions of Mexico’s south-central and southwestern coast were already seeing powerful waves as a result of Marie, and the impact was likely to spread toward the southern Baja California peninsula as the storm strengthens and moves to the northwest.

“These swells are likely to cause extremely dangerous life-threatening surf and rip current conditions,” the forecasters warned.

In Mexico, the national weather service said heavy rains threatened the states of Michoacan, Colima, Guerrero, Oaxaca, Jalisco and Nayarit.

It urged the millions of people living in those states to “exercise caution” and stay tuned for updates.