The blaze has burned more than 133,000 acres -- more than 200 square miles -- since it was first reported Aug. 17 in Stanislaus National Forest.
Firefighting teams reported "significant progress" along the western edge of the fire Sunday, the San Francisco Chronicle reported.
"We are making good progress," CalFire spokesman Daniel Berlant said. "It hasn't grown at the rate it did earlier this week."
With the fire 7 percent contained Sunday, fire crews from across the state were focusing their efforts on protecting threatened communities in Sierra Nevada foothill communities around Tuolumne City, and in Yosemite Valley, the most popular part of Yosemite National Park.
The fire has destroyed at least 23 structures and threatens more than 4,000 others, state fire officials said.
Evacuation orders were in place for Tuolumne City and the area east of Highway 108 to Mi-Wok Village and for Highway 120 from the national park boundary west to Buck Meadows. Residents of Pine Mountain Lake, a gated resort community west of Yosemite, were allowed to return home late Saturday.
There had been concern the fire might disrupt water and electricity supplies for San Francisco. There had been no interruption in the water supply by Sunday but two of the city's hydro power generating plants had to be evacuated -- forcing San Francisco to buy supplemental power under reciprocal agreements with other power companies, the Chronicle reported.
The fire is the 15th largest in the history of the state, the Los Angeles Times reported. Fed by hot, dry and windy weather, and consuming dry, dense forestation, it has doubled in size since Thursday, but the degree of spread has been less severe each of the past two days, the Chronicle reported.
InciWeb, a fire reporting service, said firefighters in some inaccessible areas are using a method known as indirect attack, where containment lines are set up away from the fire line.
The cause of the Rim fire is under investigation.
While the Rim fire was by far the largest currently burning in the state, at least nine other wildfires were burning Sunday in California. They included the Corral Complex and Orleans Complex fires in Six Rivers National Forest, which have burned about 32,000 acres between them, and the 24,000-acre American fire in Tahoe National Forest.