The so-called Rim Fire, now the seventh-largest California wildfire in records dating to 1932, has burned through 301 square miles, destroyed 111 structures and threatened water supplies, hydroelectric power and giant sequoias. Containment was at 30 percent Wednesday evening.
The fire is prompting air quality warnings more than 100 miles away in Nevada. Smokey conditions have triggered emergency warnings in the Reno and Carson City areas.
Tioga Pass Road, which is the main access road into Yosemite from the east, will be closed through Labor Day due to the wildfire.
The California National Guard on Wednesday was flying a drone above the northern edge of the park in an effort to spot other blazes. An incident commander said the unmanned MQ-1 aircraft had allowed them to spot a new fire they would not have seen from the ground.
Firefighting efforts have already cost more than $44 million since the fire erupted on Aug. 17. That's only a fraction of what's estimated to be spent during this year's fire season.
Fire officials expect full containment in approximately three weeks, but they say the fire will burn for much longer than that.
The cause of the fire remains under investigation.
The Associated Press contributed to this report.