The fire was being tackled by almost 4,000 fire personnel, including 441 firefighters.
Trump declared the California bushfires a major disaster, which allows the state and those affected to access federal funds.
Where is the Mendocino Complex Fire?
The fires in Northern California have created such a haze of smoke in the Central Valley that Sacramento County health officials advised residents to avoid outdoor activities for the entire week.
The fire itself has burned through the southern portion of the Mendocino National Forest and continues to threaten surrounding towns.
A brand new blaze called the Holy Fire was ignited on Monday in Orange County, quickly expanding to more than 1,200 acres.
McLean said firefighters are using direct means to prevent the twin fires from reaching evacuated urban areas on the east side of Clear Lake.
According to a statement from Cal Fire, full containment is expected on September 1.
Mendocino Complex Red circles on this live-updating map are actively burning areas, as detected by satellite.
It's the largest of eight major wildfires burning out of control across California, and that have claimed the lives of 7 people.
Gilless said the reason California's wildfires are so destructive this year is the state's "high heat, low relative humidity, high wind speeds and high fuel loading".
On the two fires 75 residences have been destroyed and another 9,300 remain threatened.
There have been no fatalities reported as a result of the Mendocino Complex Fire so far. That includes a great-grandmother and her two great-grandchildren, all of whom died in their Redding, Calif., home as a result of the Carr Fire.
'Look how big it got, just in a matter of days.
The Mendocino Complex Fire grew under conditions ripe for an aggressive, fast-moving wildfire. "Must also tree clear to stop fire spreading!" Officials are investigating the cause of both. Here are the 10 largest fires in California history.
Of the 20 monster fires now on the list, 16 have occurred since 1999. Sparks from power lines have also been known to spur massive infernos, as well as lightening.
NASA astronaut Ricky Arnold - a crewmember on the ISS' current Expedition 56 along with Gerst and four other spaceflyers - posted some fire photos of his own via Twitter today (Aug. 6).
The Pentagon announced Monday that it will send about 200 soldiers from Joint Base Lewis-McChord in Washington state to help with the firefighting efforts.
Officials from the California Department of Forestry and Fire Protection (CalFire) and the National Interagency Fire Center in Boise, Idaho, stressed that wild-land blazes are battled primarily by crews hacking away at dry brush with hand tools and bulldozers, not with water.