The hurricane was projected to stay well off the Mexican coast for several days before bending east over cooler waters and hitting the Baja California Peninsula as a Category 1 or Category 2 hurricane sometime Wednesday.
Authorities in the resort city of Acapulco closed the port to small craft after Rick kicked up heavy waves and gusts of wind. Acapulco's Civil Protection Department had warned that rains from the outer bands of the storm could cause landslides and flooding in the resort city, but no such effects were reported.
At 11 p.m. EDT Saturday (0300 GMT Sunday), the storm's center was located about 295 miles (475 kilometers) southwest of Manzanillo, Mexico.
Rick is the second-strongest hurricane in the eastern North Pacific since 1966, when experts began keeping reliable records, said Hurricane Center meteorologist Hugh Cobb.
The strongest was Hurricane Linda, which generated maximum winds of 185 mph (296 kph) in September 1997.
"Rick is probably going to go into the record books as one of the most rapidly intensifying hurricanes," Cobb said, adding that the storm had "ideal" conditions for growth: "very warm ocean temperatures and virtually no wind shear in the upper levels of the atmosphere."
The storm was generating waves up to 50 feet (15 meters) high near its core, Cobb said, with reports of 16-foot (5-meter) seas off the Mexican coast and "large and dangerous surf" along the coast.
Cobb said that while the storm could possibly strengthen slightly, it has probably peaked, and is expected to begin weakening in the coming days as it passes over cooler waters.
He said the storm's danger should not be underestimated, however, as Rick will still have the potential as a Category 1 or Category 2 storm to provoke heavy rains and unleash mudslides once it approaches Baja.
Cobb also noted that Rick is a very large storm, with hurricane-force winds extending outward up to 45 miles (75 kilometers) and tropical-force winds extending outward up to 155 miles (250 kilometers).
Cobb said it is still uncertain whether the eye of the storm will make landfall.
Rick was forecast to pass near Socorro Island, about 300 miles (500 kilometers) southwest of Cabo San Lucas, on Tuesday. The island is a nature reserve with a small Mexican Navy post and it hosts scuba-diving expeditions in winter months.