Thousands flee out-of-control wildfires in California and Nevada

Fast-moving wildires in California and Nevada left tens of thousands of people under mandatory evacuation orders, numerous structures threatened and air quality impacted Sunday, as a dangerous heat wave grips much of the Southwestern U.S.

The big picture: Nevada Gov. Joe Lombardo declared an emergency Sunday in response to the Davis Fire, south of Reno, where evacuation orders affected some 20,000 people were evacuated, and California Gov. Gavin Newsom proclaimed an emergency in San Bernardino County a day earlier over the Line Fire, where over 11,000 people were under evacuation orders.

By the numbers: The uncontained Line Fire is one of seven large blazes in California and 68 large fires burning across the western U.S. as of Sunday, according to the National Interagency Fire Center (NIFC). Nevada faced two large fires.

Threat level: The Line Fire has razed nearly 17,500 acres and threatened more than 35,400 structures has injured at three firefighters, per Cal Fire.

Evacuation orders were in effect for much of San Bernardino County which, along with and parts of Riverside County, was under an excessive heat warning through Monday evening, as the fire burned in the foothills of the San Bernardino Mountains.
In Los Angeles County, Angeles National Forest visitors were being evacuated Sunday evening after a wildfire erupted north of Glendora and exploded in size to 800 acres at 0% containment, Inciweb, an interagency website that tracks wildfires.
In Northern California, Cal Fire said the Boyles Fire had displaced about 4,000 residents in evacuations as it burned at 10% containment — razing some 30 structures and 40-50 vehicles in Clearlake, Lake County, and 76 acres as of Sunday evening.

Across the border, fire officials in Nevada said the Davis Fire had grown to 6,500 acres as it burned out of control. It has impacted “multiple structures,” per a Washoe County online post.

Zoom out: In addition to California and Nevada, UCLA climate scientist Daniel Swain said on X that extreme fire behavior was “occurring on numerous large wildfires in Idaho,” including the Lava Fire, and also in Oregon, and Wyoming.

Firefighters were tackling 23 large fires in Oregon, 19 in Idaho, 13 in Montana and five in Wyoming, according to the NIFC.
Several of the fires in California, Oregon, Washington and Idaho are forming their own thunderstorms, with extreme and shifting winds at the surface, making it more difficult for firefighters to fight the flames.

What we’re watching: Excessive heat warnings remained in effect across Southern California through Monday evening as the rare September heat wave continues.

Cities affected by warnings include San Diego and Los Angeles, where temperatures climbed to 112°F Sunday — just 1°F shy of the city’s all-time high temperature record.
Meanwhile, the South Coast Air Quality Management District extended a wildfire smoke advisory through Monday for San Bernadino, Riverside, Orange and L.A. counties.
Red flag warnings were in effect Los Angeles through 11pm Monday local time, and multiple red flag warnings were in place in parts of Nevada, Oregon, Washington and Wyoming.

Between the lines: Human-caused climate change is leading to more frequent, severe and longer-lasting heat waves while also driving an uptick in large wildfires in the West, among other trends.