Hurricane Orlene has strengthened while heading for an expected landfall early next week on Mexico's northwestern Pacific coast.

The US National Hurricane Centre said Orlene had maximum sustained winds of 130km/h at mid-afternoon. It was centred about 315km south-southwest of Cabo Corrientes and moving north at 7km/h.

Orlene's eye is expected to pass near or over the Islas Marias, a former Mexican penal colony the government is trying to convert into an ecotourism centre.

The storm is forecast to make landfall in Sinaloa state, in the region around the resort city of Mazatlan.

Orlene might bring heavy rains and high winds to the Pacific coast resort of Puerto Vallarta as it passes offshore, forecasters said.

Puerto Vallarta closed its port to ship and boat traffic Saturday as a precaution.

Mexico's National Water Commission said Orlene could cause "mudslides, rising river and stream levels, and flooding in low-lying areas."