RISING TEMPERATURES ARE posing new challenges for firefighters who have made incremental progress against a massive wildfire in central California which has become the biggest blaze in the state so far this year.

More than 870 remote homes and other structures at the northern edge of Los Padres National Forest are threatened by the Gifford Fire, which grew overnight after burning out of control for days.

The fire has scorched at least 339 square kilometres of Santa Barbara and San Luis Obispo counties, with only 9% of it contained.

It has scorched more land than the extensives fires that caused chaos in Los Angeles and San Diego in January, when around 230 square kilometres of land was burned. Around 200,000 people had to evacuate during those fires, with 30 people killed and 18,000 homes and structures destroyed.

Crews are working in steep, inaccessible terrain to fight the latest wildfire.

Temperatures were around 35 degrees Celsius today and are anticipated to rise to above 38 degrees tomorrow, said Captain Scott Safechuck with Santa Barbara County Fire Department.

“We have hot weather, and we have low relative humidity,” he said. “So we expect extreme fire behaviour.”

He said that winds are fortunately expected to remain relatively calm.

However, wildfire risk will be elevated through the weekend across much of inland California as the heatwave intensifies.

Smoke from the Gifford Fire fills the sky over Los Padres National Forest PA PA

The southern part of the state has seen very little rain, drying out vegetation and making it “ripe to burn”, the National Weather Service for Los Angeles warned in a statement.

Temperatures around 38 degrees are forecast for the Sacramento Valley.

More than 2,200 personnel are battling the Gifford Fire, which grew out of at least four smaller fires that erupted on Friday along State Route 166, forcing closures in both directions east of Santa Maria, a city of about 110,000 people.

The causes of the fires are under investigation.

Flames are racing through a vast, mostly unpopulated region that includes forests, ranches, large canyon properties and agricultural parcels growing wine grapes and strawberries.

The weather service warned of health risks from spreading smoke that could affect much of south-west California.

Officials reported four injuries, including a firefighter who was treated for dehydration.

Over the weekend, a motorist was treated in hospital for burn injuries after getting out of his vehicle and being overrun by flames, and two contract employees assisting firefighters were hurt when their all-terrain vehicle overturned.

Additional reporting by Lauren Boland

Unsure of what exactly is happening with the earth’s climate? Check out our FactCheck Knowledge Bank for essential reads and guides to finding good information online.