FELTON (United States) • California's lightning-sparked wildfires more than doubled in size into some of the largest in state history on Friday, with one blaze advancing to within 1.6km of the University of California Santa Cruz (UCSC).
At least six people have died, 43 firefighters and civilians have been injured, and more than 500 homes and other structures destroyed as fires have burned an area larger than the US state of Rhode Island.
Firefighting forces were depleted as they fought around 560 blazes.
Only 45 of 375 out-of-state fire crews requested by California had arrived, said a spokesman for wildfire authority Cal Fire.
The state has been hit by its worst dry-lightning storms in nearly two decades.
Close to 12,000 lightning strikes have sent fire racing through lands parched by record-breaking heat, forcing 175,000 people to evacuate their homes, largely in Northern California.
The lightning strikes, driven by record temperatures, were a consequence of climate change and more such storms are expected today, Governor Gavin Newsom told a news conference on Friday.
"If you are in denial about climate change, come to California," Mr Newsom told the Democratic National Convention on Thursday.
One of the hottest air temperatures recorded anywhere on the planet in at least a century, and possibly ever, was reached last weekend at Death Valley in California's Mojave Desert, where it soared to 54.4 deg C.
Most of the fires are in the San Francisco Bay Area, with a complex of blazes east of Palo Alto and another in Wine Country south of Sacramento now the seventh and 10th largest in state history, respectively, according to Cal Fire.
In Santa Cruz, a city of around 65,000, residents were told to have evacuation "go bags" at the ready.
Bulldozers dug fire lines on the northern flank of the UCSC campus, around 4.8km north-west of the coastal city's boardwalk. Videos showed giant redwood trees, some over 2,000 years old, standing largely unscathed among the torched ruins of buildings in California's oldest state park to the north.
"The fire continues to advance, and much of what will happen next depends on weather conditions such as wind direction and speed," UCSC chancellor Cynthia Larive wrote in a tweet, after ordering the evacuation of the campus.