Firefighters faced "extremely dangerous" conditions Monday as they battled to save a community of 8,000 residents, with lightning strikes threatening to worsen a blaze that has already killed at least two people and become California's biggest fire of the year.
Hundreds of personnel were involved in the fight against the fast-moving McKinney Fire, which has torn through more than 55,000 acres (22,000 hectares) near the border with Oregon, forcing thousands from their homes.
The National Weather Service meanwhile issued a warning because of the threat of dry lightning -- powerful electrical strikes that come without any of the desperately needed rain.
"These conditions can be extremely dangerous for firefighters, as winds can be erratic and extremely strong, causing fire to spread in any direction," said CalFire, an interagency website that collates fire information.
California, along with much of the western United States, is in the grip of its worst drought in more than 1,000 years.
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The drought, exacerbated by man-made climate change, has left the countryside parched and exceedingly vulnerable to the wildfires that naturally break out, making the blazes hotter, faster and more destructive.
The McKinney Fire on Sunday claimed its first human lives, with the Siskiyou County Sheriff's Office saying firefighters found two people dead inside a burned-out car in the driveway of a home in the town of Klamath River.
Sheriff Jeremiah LaRue said the pair were likely caught in the swift-moving fire as they tried to flee.
California Governor Gavin Newsom has declared a state of emergency in Siskiyou County, and more than 2,000 residents of the rural area are under evacuation orders.
A heat wave with temperatures of over 100 degrees Fahrenheit (38 degrees Celsius), tinder dry terrain and thunderstorms packing strong winds are complicating the efforts of firefighters battling the blaze.
"Fire growth is expected to spread in all directions," the Klamath National Forest service said in a statement. "Warning for thunderstorms and lightning. Gusty outflow winds of 30 to 50 mph (50 to 80 kph) will be possible near thunderstorm cells."
According to the Siskiyou County Sheriff's Office, the fire has destroyed more than 100 structures -- including homes, a grocery store and a community center -- in the area surrounding Yreka, though it has not yet encroached upon the town of about 7,800 people.
"Surrounding areas should be ready to leave if needed. Please don't hesitate to evacuate," the county sheriff tweeted.
The McKinney fire is California's largest wildfire so far this year -- though it remains much smaller than last year's Dixie Fire, which burned nearly one million acres.
An AFP journalist working in the fire area captured a photograph of a kitten with singed whiskers cowering in between rocks in the Klamath National Forest.
As the picture ricocheted around the internet, users asked for updates, with one seemingly offering to look after the animal.
"Do you know if this kitten has been cared for and adopted at this point?" tweeted @bobbiescat
Another journalist shared footage of a young puppy gratefully lapping at a bowl of water after emerging from the ashen ruins of a home in Klamath River.
Rescue Ranch Yreka, which took in the stricken pup, said it had received nearly 140 dogs in less than two days, and appealed for donations to help feed and care for them.
The fast-spreading blaze comes just days after the Oak Fire near Yosemite National Park destroyed dozens of buildings and forced thousands to evacuate.
California still has months of fire season ahead of it.
Other parts of the world have also faced intense wildfires this year, as scientists say climate change is making heatwaves more frequent and more intense, increasing the risk of fires.
In Portugal, a blaze broke out in the Mafra area, north of Lisbon, over the weekend while in France at least four firefighters were seriously injured and motorways were closed.
Also over the weekend, hundreds of firefighters battled a blaze in eastern Germany, with four people injured.