The Tuolumne County Sheriff's Office, meanwhile, issued evacuation advisories for Tuolumne and nearby Ponderosa Hill, said InciWeb, a federal website that collects information from agencies like the U.S. Forest Service and Bureau of Land Management. It was not clear how many residents were covered by the evacuation advisory.
Evacuations also remained in place for areas south of Highway 120 (including Scotts Ridge), north of Old Yosemite Road and along the Highway 108 corridor between Tuolumne City and Pinecrest.
Authorities say the Rim Fire started on August 17. The cause is under investigation.
"There's a lot of concern, and there's a lot of work to be done," U.S. Forest Service spokesman Lee Bentley said.
Firefighters were able to build fire lines in several locations Tuesday. The forecast is also looking favorable as daytime highs sink into the 70s over the Labor Day weekend, a break from the temperatures in the high 80s firefighters were facing Wednesday.
"Access and difficult terrain remain concerns for crews and equipment," said an incident report. "Rapid fire growth and extreme fire behavior are hampering suppression efforts."
As many as 20 helicopters and air tankers were aiding the efforts.
A top priority is stopping the fire from spreading farther in Yosemite National Park.
The Merced and Tuolumne giant sequoia groves, while not in imminent danger, were closed as firefighters conduct preventative measures to protect the majestic trees.
Yosemite, with hundreds of campground sites and lodging units, had nearly 4 million visitors last year, the National Park Service said. The park typically has 15,000 visitors on a busy summer weekend.
About 4,500 structures, many of them vacation homes, were under threat, InciWeb said. The fire has cost more than $39 million to date.
Thirty-one residences and 80 outbuildings have been destroyed.