Image copyright Getty Images Image caption Firefighters have scorched combustible vegetation in an attempt to control the fires

California's fire protection chief has warned that devastating wildfires could worsen again over the weekend due to dry air and strengthening winds.

Ken Pimlott said several thousand extra firefighters deployed on Friday were fighting 17 separate blazes.

Northern California is suffering the most lethal outbreak of wildfires in the state's history, with 35 people dead and more than 90,000 evacuated.

The blazes have raged since Sunday, destroying an estimated 5,700 homes.

Firefighters had made some headway on Friday, clearing dry vegetation and other combustible fuels around populated areas on the fires' southern flank.

But high temperatures and strong winds were forecast to return on Saturday, with gusts of up to 55 mph (90 kph) and 10% humidity.

"If new fires start they could spread extremely rapidly," warned Brooke Bingaman, a National Weather Service meteorologist in Sacramento, California.

"Those fuels are super dry right now. This also could cause problems for the current wildfires and the firefighters who are trying to suppress them."

Media playback is unsupported on your device Media caption California districts wiped out by wildfires

A total of 17 major wildfires have scorched nearly 222,000 acres of dry brush, grasslands and trees across eight counties in California's wine country.

The 35 confirmed deaths so far make the so-called North Bay fires the deadliest in California history - surpassing the 29 deaths in LA's Griffith Park fire of 1933.

And that figure is likely to rise, authorities said. As of Friday there were 235 people still missing in Sonoma County alone.

Image copyright Reuters Image caption Firefighters dig through a burnt-out home. Hundreds of people are still missing

The huge fires have sent smoke and ash over San Francisco, about 50 miles away, and over some towns and cities even further south.

And the blaze has devastated businesses in the region, famous for its wine production. At least 13 Napa Valley wineries have been destroyed, a trade group said.

The owner of Paradise Ridge winery in Santa Rosa, Rene Byck, told the BBC that the blazes had destroyed millions of dollars worth of wine.

"We lost about 7,500 cases, 8,000 cases of wine... The wine in this building was probably worth around $4,000,000."

California governor Jerry Brown said he planned to visit the area with two US senators on Saturday.

"We'll keep working day and night with our local and federal partners to fight these fires and help residents get back on their feet in these trying times," he said.