The storm soaked beaches on the mainland's Pacific coast before turning toward Baja California, where it was scheduled to nick the peninsula's southern tip on Friday. It was downgraded to Category 2 with maximum sustained winds of 105 mph.
John wasn't likely to affect the United States — cooler Pacific waters tend to diminish storms before they reach California.
Officials were preparing to evacuate 10,000 people in Cabo San Lucas and San Jose del Cabo and at least 5,000 others in La Paz, the capital of the state of Baja California del Sur. Shelters had been set up in 131 schools.
"We are going to give priority to the most-vulnerable zones where there's the most need," said Victor Guluarte, the state's Interior Secretary.
Shop owners boarded up windows and hotel workers stripped rooms of light fixtures and furniture, in case plate-glass windows were shattered.
John was moving northwest at 13 mph. Its outer bands were expected to begin affecting Cabo San Lucas early Friday, and a hurricane warning was issued for the peninsula's southern tip, also home to the resort of San Jose del Cabo.
Forecasters at the U.S. National Weather Center in Miami warned John could drop up to 18 inches of rain in some places and create up to a 5-foot storm surge. The weather center warned of "life-threatening flash floods and mudslides" in mountain areas.
Residents emptied grocery shelves of food and water, and endured long waits for gasoline. At the airport, hundreds of tourists battled for seats on the few planes heading out of the isolated peninsula. Driving out wasn't much of an alternative — there's only one narrow road, 400 miles long, leading to Tijuana.
Among those hoping to get out was 61-year-old Linda Laport, who was vacationing with family a year after Hurricane Katrina flooded her New Orleans home and claimed her father's life, she said.
"We heard there was a hurricane coming — we were not going to take no chances," she said.
Junichi Hriata, 33, was also sick of hurricanes. The 33-year-old journalist from Tokyo was vacationing in Cancun last year when Hurricane Wilma hit, and he spent a week in a shelter without electricity or showers.
"I'm not going through that experience again," he said. "It was hell."
Bill Crowley, a 42-year-old tourist from Lakewood, Colo., was collecting seashells and swimming in the Pacific with his wife when strong gusts of wind forced even die-hard beachgoers to head for cover. He said he would ride the storm out in his beachfront hotel room.
"There's no other place to go," he said. "I would evacuate the first floor of these hotels, but we're on the third floor so we should be all right."
By Thursday afternoon, there was still a hurricane warning for the bay that is home to the mainland resort of Puerto Vallarta, made famous by the 1964 movie "The Night of the Iguana." But the city appeared to have escaped the storm's wrath.
Skies were cloudy but no rain was falling as local residents walked to work and a handful of tourists strolled along the waterfront promenade in front of a calm sea.
In Cabo San Lucas, fishermen were tying down their boats, and Port Capt. Everardo Jimenez said he had ordered a tourist boat out of the water.
Hotel workers stripped rooms of light fixtures and furniture, in case plate glass windows were blown out.
Antonio Juarez, a 23-year-old construction worker, was nailing sheets of plywood across the windows of a beachfront condominium Thursday.
"The last one hit us, and hit us hard," he said of Hurricane Ignacio, which blew through the area two years ago. "We've learned how to take precautions."
Meanwhile, Hurricane Kristy formed far out to sea, but forecasters said some interaction was possible. If that happened, Kristy would likely be absorbed by the larger John, forecasters said.
Officials name both Atlantic and Pacific hurricanes in alphabetical order.