Firefighters hope shifting winds and cooling temperatures over the next few days will help them battle a wildfire in a forest in California’s far north that has displaced thousands of people and burned at least 100 structures.

Authorities have arrested a 30-year-old woman on suspicion of starting the Fawn Fire in the Mountain Gate area north of the city of Redding in the US state.

The blaze covered more than 10 square miles and was 10% contained on Friday night, according to the California Department of Forestry and Fire Protection (Cal Fire).

California Highway Patrol said nearly 2,000 residents were under mandatory evacuation orders on Friday and another 7,400 were under evacuation warnings.

Damage inspection teams are expected to conduct assessments on Saturday.

Cal Fire said 9,000 structures were threatened by the fire and at least 100 structures had burned. Photos and video showed some homes burning but the number of residences lost was not known.

The fire erupted at 4.45pm on Wednesday (12.45am BST on Thursday) and grew explosively in hot and gusty weather the following day in the region about 200 miles north of San Francisco.

Firefighter tackles blaze
Firefighter Ron Burias battles the Fawn Fire as it spreads north of Redding, California (AP)

North north-east winds on Friday night are expected to shift to become south south-west winds and be in firefighters’ favour, Cal Fire said.

However, firefighters will likely encounter steep terrain during their efforts to control the blaze in the coming days.

Temperatures are likely to slowly drop over the next several days as a cooling-off period comes, officials said.

Alexandra Souverneva, 30, of Palo Alto, is under arrest on suspicion of starting the fire, Cal Fire said.

A helicopter drops water
A helicopter drops water on the Fawn Fire burning north of Redding in Shasta County (AP)

Workers at a quarry reported seeing a woman acting strangely and trespassing on Wednesday. Cal Fire said Souverneva later walked out of the brush near the fire line, approached firefighters and told them she was dehydrated and needed medical help.

During an interview with Cal Fire and law enforcement, officers came to believe Souverneva was responsible for setting the fire.

She was booked into the Shasta County Jail.

Souverneva, who had a lighter in her pocket when she approached firefighters, was charged on Friday with felony arson to wildland with an enhancement due to the declared state of emergency California is under, said Shasta County District Attorney Stephanie Bridgett.

The woman is also being investigated for starting other fires in Shasta County and throughout the state, Ms Bridgett said.

The Fawn Fire is the latest destructive fire to send Californians fleeing this year. Fires have burned more than 3,600 square miles so far in 2021, destroying more than 3,200 homes, commercial properties and other structures.

Wildfire
A firefighter uses a drip torch to slow the Fawn Fire burning north of Redding (AP)

Those fires include two big forest blazes growing in the heart of California’s giant sequoia country on the western slope of the Sierra Nevada.

Smoke from those fires raised air quality concerns in the San Joaquin Valley below the Sierra and also darkened skies over greater Los Angeles on Thursday.

South coast air regulators issued a smoke advisory but said the heaviest smoke would remain in the upper atmosphere and impacts on surface air quality would be in local mountain ranges.

Historic drought tied to climate change is making wildfires harder to fight. It has killed millions of trees in California alone.

Scientists say climate change has made the west much warmer and drier in the past 30 years and will continue to make weather more extreme, with wildfires becoming more frequent and destructive.