Thousands told to flee raging California wildfire

Thousands of people have been ordered to evacuate as a wildfire rages out of control in northern California, with a swathe of the United States in the grip of a "record-breaking and dangerous" heatwave that was complicating firefighting efforts.

More than 3,500 acres of grass and woodland have been consumed since Tuesday when a blaze erupted just outside Oroville.

The town, near the state capital of Sacramento, is just 38 kilometres from Paradise, a community that was razed in 2018 by the deadliest fire in California history, which claimed the lives of 85 people.

Garrett Sjolund, fire chief of Butte County, said the area was under a so-called "red flag warning".

"The conditions out there that are in our county this summer are much different than we've experienced the last two summers," he told reporters.

"The fuels are very dense. Brush is dry, and as you can see, any wind will move a fire out very quickly."

Over 25,000 people in the area were under orders to evacuate on Wednesday, local NBC affiliate KCRA reported.

Climate scientists say the western US is undergoing a decades-long aridification as weather patterns change, at least in part because of human-caused global warming.

California suffered around 20 years of drought, but the last two years were relatively mild, with near-record amounts of rain that filled reservoirs and sparked furious growth in forests and grasslands.

However, 2024 is shaping up to be a hot and dry year, and that flora is rapidly drying out, creating plenty of fuel for the wildfires that are a normal part of the ecosystem's natural cycle.

The conditions have left officials warning of potentially devastating blazes waiting to happen, especially if people are careless or negligent with fireworks over the July 4th Independence Day holiday.

"We've had four fires within the last couple of weeks. This is a bad fire season," said Butte County Sheriff Kory Honea.

"The last thing we need is somebody who's purchased fireworks from a local fire stand going out and doing something stupid. Don't be an idiot."

On Wednesday, around 1,400 firefighters were attacking the flames on the ground with heavy machinery and by air with planes and helicopters, dumping red fire suppressant.

Sjolund said that equipment and personnel were arriving from other jurisdictions to reinforce operations.

A handful of people, including some firefighters, have reportedly been injured, though none of them seriously.

Extreme weather events are becoming increasingly common as our planet warms, largely due to humanity's unchecked burning of fossil fuels since the start of the Industrial Revolution.