Firefighters helped by cooler weather as they battle huge blaze in California

Thousands of firefighters battling a wildfire in northern California have received some help from the weather, hours after it exploded in size.

The blaze was one of several tearing through the western United States and Canada, fuelled by wind and heat.

Cooler temperatures and an increase in humidity could help slow the Park Fire, the largest this year in California.

Its intensity and dramatic spread led fire officials to make unwelcome comparisons to the monstrous Camp Fire, which burned out of control in nearby Paradise in 2018, killing 85 people and torching 11,000 homes.

Paradise again was near the danger zone. The entire town was under an evacuation warning, one of several communities in Butte County. Evacuation orders were also issued in the counties of Plumas, Tehama and Shasta.

An evacuation warning calls for people to prepare to leave and await instructions, while an evacuation order means to leave immediately.

Temperatures are expected to be cooler than average through the middle of next week, but “that doesn’t mean that fires that are existing will go away”, said Marc Chenard, a meteorologist at the National Weather Service Weather Prediction Centre in College Park, Maryland.

As of Saturday night, the Park Fire had scorched 547 square miles and destroyed 134 structures since igniting on Wednesday, when authorities said a man pushed a burning car into a gully in Chico and then fled. It was 10% contained and moving to the north and east near Chico.

The fire is larger than the city of Los Angeles, which covers about 469 square miles, and now ranks seventh on the list of the state’s top 10 largest wildfires by acreage, Cal Fire said in a social media post.

Nearly 2,500 firefighters were battling the blaze, aided by 16 helicopters and numerous air tankers.

Jeremy Pierce, a Cal Fire operations section chief, said firefighters were taking advantage of the cooler weather while it lasts: “We’re having great success today.”

Overall more than 110 active fires covering 2,800 square miles were burning in the US as of Friday, according to the National Interagency Fire Centre.

In southern California, a blaze in the Sequoia National Forest swept through the community of Havilah after burning more than 48 square miles in less than three days. The town of 250 people had been under an evacuation order.

Crews were also making progress on a series of fires in the Plumas National Forest near the California-Nevada border, Forest Service spokesperson Adrienne Freeman said. Traffic was backed up for miles near the border along the main road linking Los Angeles and Las Vegas.

The most damage so far has been to the Canadian Rockies’ Jasper National Park, where 25,000 people were forced to flee and the park’s namesake, a World Heritage site, was devastated, with 358 of the town’s 1,113 structures destroyed.

Late Friday in eastern Washington, crews stopped the progress of a fire near Tyler that destroyed three homes and five outbuildings, the Washington Department of Natural Resources said.

Two fires in eastern Oregon burned about 660 square miles.

And in Idaho, homes, outbuildings and a commercial building were among structures lost in several communities including Juliaetta, which was evacuated on Thursday.