A teenager has died at a hospital four days after suffering head injuries in a fall at Yosemite National Park, in a deadly year for visitors to the California nature reserve, authorities said on Thursday.

Kao Kue, 17, died at Doctor's Medical Center in Modesto, in central California, on Wednesday, a Stanislaus County coroner's clerk said.

An air ambulance had flown Kue to the hospital after he suffered head injuries at Yosemite on Saturday when he fell on the steep and rocky Mist Trail, a popular feature at the park, officials said.

Fourteen visitors have died this year at Yosemite, which has seen six drownings, two fatal falls, one death by car accident and five by natural causes, said Park Ranger Jessica Chamberlain.

Last year the park had a record 15 fatalities, but typically five to six people die there each year, she said.

Although he was seriously hurt in the park, Kue's death does not count toward the annual total for Yosemite fatalities because he died outside the park's boundaries, she said.

Further details on the circumstances of the boy's injuries and death were withheld by park officials due to his age.

Park officials are not planning to install more signs or other protections for visitors due to the higher than average number of fatalities this year, Chamberlain said.

"We are adamant about educating all of Yosemite's visitors about potential dangers, as well as ensuring that it remains a wild place," Chamberlain said.

The high number of drownings at Yosemite this year comes as the park's rivers and streams have swollen due to unusually heavy snowfall over the winter.

"The rivers are still high," Chamberlain said. "We are asking visitors to use caution and common sense."