California firefighters have taken advantage of milder temperatures to gain considerable ground on a wildfire that had grown to almost the size of Los Angeles.

It comes after officials said it would take until next month to fully contain the blaze, which is the largest in the US state’s history.

The Mendocino Complex fire is 47% contained, according to the California Department of Forestry and Fire Protection (Cal Fire). Yesterday, the blaze was 34% contained.

So far, two firefighters have been injured fighting the blaze, which has destroyed more than 300,000 acres.

While sprawling, the wildfire is less destructive than last week's Carr Fire near Redding, destroying 75 homes and forcing the evacuation of more than 23,000 people.

The Carr Fire destroyed more than 1,000 structures.

Some 4,000 firefighters are working to stop the fire from reaching communities at the southern tip of the Mendocino National Forest north of San Francisco.

The blaze is still threatening more than 10,000 structures, Cal Fire said.

The Mendocino Complex is one of 17 major fires burning in California that have destroyed more than 1,500 structures and displaced tens of thousands of people in the past month.

"Tonight fire crews will continue to take advantage of the lower temperatures to increase containment lines," the agency said in an advisory as the temperatures in the area remained near 60 degrees Fahrenheit (15 Celsius).

The agency has set 1 September as the new date for expected full containment of the Mendocino Complex.

The fire became the largest in California history on Monday, after officials began battling two separate blazes in the Mendocino area as a single event, according to Cal Fire.

Now, having scorched more than 300,000 acres, the blaze has surpassed the Thomas Fire, which burned 281,893 acres in Santa Barbara and Ventura counties in southern California last December, destroying more than 1,000 structures.

Since Sunday, US President Donald Trump has claimed, without substantiating his remarks, that California was letting water run into the ocean instead of using it to fight blazes, and he blamed California's environmental policies for worsening the fires.

The comments baffled California firefighters, who said they had more than enough water to douse the flames.

Climate change is widely blamed for the higher temperatures that have fueled wildfires in California, and further afield like in Portugal, Sweden and Siberia.

The California fires are on track to be the most destructive in a decade, prompting Democratic Governor Jerry Brown and Republican leaders such as state Senator Ted Gaines to call for thinning forests and controlled burns to reduce fire danger.

Environmentalists oppose such preventive burns, saying they kill wildlife.