The wildfire that has engulfed the northwest edge of Yosemite National Park is now so massive that it has begun to create its own weather pattern and is becoming the largest wildfire recent California history, authorities said Sunday.

Dubbed the Rim Fire, the blaze encompassed 203 square miles by Sunday. Despite the efforts of more than 2,600 firefighters assisted by planes and helicopters, it was only 7 percent contained, according to the California Department of Forestry and Fire Protection.

The Rim Fire has been burning for eight days, having started Aug. 17 in a remote canyon of the Stanislaus National Forest. Exacerbated by dry conditions and heavy brush, the fire has grown to a point where it threatens thousands of rural homes, two groves of ancient sequoias, and the water supply and electrical resources of San Francisco.

Immediate attention has been put on preserving the sequoias, which are among the largest and oldest living things on earth. The trees grow only on the western slopes of the Sierra Nevada. Though they can resist fire, park officials want to take extra precautions to ensure their safety. Firefighters are clearing brush and setting sprinklers to protect the Tuolumne and Merced groves, which contain about three dozen trees. 

"All of the plants and trees in Yosemite are important, but the giant sequoias are incredibly important both for what they are and as symbols of the National Park System," park spokesman Scott Gediman said Saturday.

Meanwhile, California Gov. Jerry Brown has declared a state of emergency for San Francisco as the fire is burning not far from the city's power lines and only four miles away from the Hetch Hetchy reservoir, which provides the city with 85 percent of its water. Two of San Francisco's hydroelectric power plants have already been shut down due to the fire for fear that they could be contaminated by ash. 

As the Rim Fire continues to create its own weather patterns, its 30 to 40 mph winds are expected to push the fire further north into Yosemite National Park on Sunday. CBS News reports that the erratic weather could make the fire even less predictable. The fire continues to endanger about 4,500 residences and at least 23 structures have been destroyed, according to Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection.

"The wind could push it further up north and northeast into Yosemite and closer to those communities, and that is a big concern for us," Berlant added.

Communities such as Tuolumne City, Twain Harte and Long Barne are among those threatened. While popular tourist areas of Yosemite, such as Half Dome and Yosemite Falls, remain safe so far, hundreds of residents and visitors have already evacuated the area. A popular bluegrass music festival that was to take place over Labor Day weekend has been canceled. 

Firefighters are working to contain the northern edge of the Rim Fire in order to protect the nearby communities. 

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