Thousands of firefighters battling a wildfire in northern California received some help from the weather Saturday, just hours after the blaze exploded in size, scorching an area greater than the size of Los Angeles. The blaze was one of several tearing through the western United States and Canada, fueled by wind and heat.

Cooler temperatures and an increase in humidity Saturday could help slow the Park Fire, the largest blaze so far this year in California. The blaze’s intensity and dramatic spread led fire officials to make unwelcome comparisons to the monstrous Camp Fire. That fire burned out of control in nearby Paradise in 2018, killing 85 people and torching 11,000 homes.

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

Temperatures are expected to be cooler than average through the middle of the 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 Center in College Park, Maryland.

The blaze has scorched 540 square miles as of Saturday with no containment. Los Angeles covers roughly 503 square miles.

Communities elsewhere in the U.S. West and Canada also were under siege Saturday from fast-moving flames.

More than 110 active fires covering 2,800 square miles were burning in the U.S. on Friday, according to the National Interagency Fire Center. Some were caused by the weather, with climate change increasing the frequency of lightning strikes as the region endures record heat and bone-dry conditions.

In Chico, California, Carli Parker is one of hundreds who fled their homes as the Park Fire pushed close.

“I think I felt like I was in danger because the police had come to our house because we had signed up for early evacuation warnings, and they were running to their vehicle after telling us that we need to self-evacuate and they wouldn’t come back,” said Parker, a mother of five.

In eastern Washington state, crews late Friday stopped the forward progress of a fire near the community of Tyler that had destroyed three homes and five outbuildings, the Washington Department of Natural Resources said Saturday.

Elsewhere, fire crews were making progress on another complex of fires burning in the Plumas National Forest near the California-Nevada line, said Forest Service spokesperson Adrienne Freeman.

Traffic was backed up for miles near the border on a portion of the main highway linking Los Angeles and Las Vegas, as crews continued Saturday to battle a fire that started a day before when a truck carrying lithium-ion batteries crashed and turned onto its side.

The most damage so far has been to the Canadian Rockies’ Jasper National Park, where a fast-moving wildfire forced 25,000 people to flee and devastated the park’s namesake town, a World Heritage site.