Tropical storm Cristina strengthened into a category 1 hurricane on Wednesday as it moved away from Mexico's Pacific coast, prompting authorities to warn of heavy rains in the Latin American nation.

Cristina was located about 425 kilometres south of the port of Manzanillo with maximum sustained winds of 120 km/h and higher gusts, the U.S. National Hurricane Center said early Wednesday.

The hurricane was expected to gain strength, as it moved at a speed of nine km/h westward, unlikely to make landfall.

Mexican authorities warned of rising rivers and mudslides caused in southern and western Mexican states including Oaxaca, Guerrero, Michoacan, Colima and Jalisco.

Cristina could cause waves of up to four metres high in coastal areas, the National Weather Service said in a statement.

Guerrero, home of beach resort Acapulco, last year was severely affected by dual storms Ingrid and Manuel, whose unprecedented rainfall killed over 150 people.