The system, which isn't threatening land, probably will be downgraded to a tropical storm before approaching the Mexican mainland or Baja California Peninsula in the next three to five days, the center said.

"It's moving parallel to the coast," said Dave Roberts, a U.S. Navy forecaster at the National Hurricane Center. "We should see a gradual weakening trend within the next couple days."

Sergio was about 455 miles (732 kilometers) south-southwest of Manzanillo, Mexico, at 1 a.m. Pacific time, Roberts said. With sustained winds of about 105 miles an hour, the storm is just shy of the 111 mph minimum needed to be considered a major hurricane and probably won't strengthen, he said.

Sergio, the 10th Pacific hurricane of the 2006 season, was moving northeast at about 5 mph and may be turning gradually to the north, the hurricane center said in its official discussion of the storm.

Hurricane-force winds extend about 25 miles from the center of the storm and tropical-storm-force winds stretch as far as 80 miles from Sergio's eye. Strong rains extend out 93 miles from the center, Mexico's Civil Protection Directorate said.

November Storm

Sergio was named two days ago — 16 days before the end of the May-to-November Pacific hurricane season. It was the first time in 45 years that a second named storm formed in the eastern Pacific basin in November. Tropical Storm Rosa formed earlier this month.

Pacific hurricane records date back more than 50 years at the U.S. center, which coordinates tropical weather forecasts for countries along the Caribbean Sea, Gulf of Mexico, North Atlantic Ocean and eastern North Pacific Ocean.

Mexico's Civil Protection Directorate put the northwestern states of Guerrero, Michoacan, Colima, Jalisco and Baja California Sur on "Blue Alert," the lowest in a five-tier scale.