The fire broke out on Friday and has so far scorched nearly 18 square kilometres of steep, remote hillsides on the park's western edge and is burning largely out of control.

Guests were also ordered to leave the Yosemite Cedar Lodge on Saturday as flames crept up slopes and the air became thick with smoke.

"You can't see anything, it's so smoky outside. It's crazy," front desk clerk Spencer Arebalo, one of a handful of employees who stayed behind at the popular hotel inside the park, said.

"We're counting on being closed at least one more day."

Evacuations were also ordered in nearby rural communities and guests in nearby lodges and motels have been told to be ready to leave.

A stretch of State Route 140 into Yosemite was closed, and motorists were urged to find alternate routes.

Temperatures of 35C and inaccessible terrain were making it difficult for crews to slow the flames, US Forest Service fire Captain Mike Seymour said.

Fire fighter Braden Varney, 36, died in the fire on Saturday as he bulldozed a gap into the vegetation to stop the flames spreading, CalFire Fire Chief Nancy Koerperich.

Varney's body likely won't be retrieved until Monday at the earliest because it's in a "precarious location" and conditions were too dangerous over the weekend, Cal Fire Deputy Chief Scott McLean said.

The wildfire is one of several burning across the state and among 56 large blazes that are active in the US, most in the American West, a region that is struggling with drought and heat.

Australian Associated Press