The so-called Cranston Fire, which erupted on Wednesday in the San Jacinto Mountains east of Los Angeles, burned hundreds of trees and in a matter of hours grew to more than seven square miles.
As smoke from a nearby wildfire pours into Yosemite Valley, Tom Lambert has had to tell tourists who booked his vacation home months in advance that they would have to defer their dream stays so firefighters could take protective measures against the growing blaze.
That fire, about 150 miles (240 km) north of Sacramento, had blackened 20,000 acres (8,100 hectares) as of Thursday, three times its size a day earlier.
All visitors were forced to leave the park by Wednesday at noon.
The last time the 7.5-mile-long (12-kilometre-long) valley was closed because of fire was 1990, he said.
The fire was relatively calm throughout much of Tuesday night and into Wednesday morning as a heavy inversion layer kept fire activity to a minimum, officials said.
Yosemite National Park has announced that large areas of the park will be closed off as during the near-height of the visitor season due to "ongoing impacts" from the Ferguson fire.
Yosemite Valley closed to battle wildfires
It was one of five major, uncontained wildfires burning across California during a heat wave that has the state sizzling under record-shattering temperatures.
The fire quickly burned almost 2 square miles (5 square kilometers) of dry brush and timber. The glacial valley's grand vista of waterfalls and shear granite faces has been obscured by a choking haze of smoke from the Ferguson Fire.
The fire has been burning for almost two weeks in the Sierra National Forest, and has killed one firefighter who died July 14, when the bulldozer he was operating overturned.
Executive Director of the Tuolumne County Visitors Bureau, Lisa Mayo, comments, "We know that visiting Yosemite is very special and for some visitors, this is their trip of a lifetime, so we are trying to do everything we can to give them the best experience possible under the circumstances".
Burning its way across steep, rugged terrain with little or no road access, containing the fire has been hard and has left the splendid landscapes of Yosemite cloaked in hazy smoke.
An estimated 2,000 people were inside the park as of Tuesday, officials said. "Some want to ride it out for a few days and see if they can get back in the park".
For current conditions, trip planning, and more information visit the Sequoia and Kings Canyon National Parks website.
"There are wonderful places to visit in the region, so we're asking people to consider alternative plans", he said.