MEXICO CITY - Hurricane Roslyn plowed over the Pacific as a powerful Category 4 storm just offshore from the Mexican resort of Puerto Vallarta while heading for a Sunday landfall a little to the north.

The U.S. National Hurricane Center said Roslyn had maximum sustained winds of 215 kph late Saturday but might lose some power during the night.

Roslyn's core was about 105 kilometers west-southwest of Cabo Corrientes - the point of land jutting into the Pacific south of Puerto Vallarta - and moving north at 19 kph.

Forecasters said Roslyn likely would pass close to Cabo Corrientes and the Puerto Vallarta region during the night but warned that those areas would still see high winds, heavy rains and rough surf.

The storm was expected to come ashore in Nayarit state Sunday morning. Hurricane Orlene made landfall Oct. 3 a little farther north in roughly the same region, about 75 kilometers southeast of the resort of Mazatlan.

Hurricane-force winds extended out 45 kilometers from Roslyn's center, while tropical storm-force winds extended out to 130 kilometers, the U.S. hurricane center said.

A hurricane warning was posted on a stretch of coast from Playa Perula south of Cabo Corrientes north to El Roblito and for the Islas Marias.

Seemingly oblivious to the approaching storm, tourists ate at beachside eateries Saturday around Puerto Vallarta and smaller resorts farther north on the Nayarit coast where the storm likely was headed.

"We're fine. Everything is calm, it's all normal," said Jaime Canton, a receptionist at the Casa Maria hotel in Puerto Vallarta. He said that if winds picked up, the hotel would gather up outside furniture "so nothing will go flying."

While skies began to cloud up, waves remained normal, and few people appeared to be rushing to take precautions. Swimmers were still in the sea at Puerto Vallarta.

"The place is full of tourists," said Patricia Morales, a receptionist at the Punta Guayabitas hotel in the laid-back beach town of the same name, farther up the coast.

Asked what precautions were being taken, Morales said, "They (authorities) haven't told us anything."

The Nayarit state government said the hurricane was expected to make landfall around the fishing village of San Blas, about 150 kilometers north of Puerto Vallarta.

The head of the state civil defense office, Pedro Núnez, said, "Right now we are carrying out patrols through the towns, to alert people so that they can keep their possession safe and keep themselves safe in safer areas."

In the neighboring state of Jalisco, Gov. Enrique Alfaro wrote that 270 people had been evacuated in a town near the hurricane's expected path and that five emergency shelters had been set up in Puerto Vallarta.

The National Water Commission said rains from Roslyn could cause mudslides and flooding. and the U.S. hurricane center warned of dangerous storm surge along the coast, as well as 10-15 centimeters of rain.