Hundreds of wildfires are burning in California, 100,000 people are under evacuation orders, and the governor is calling in help from 10 U.S. states, Canada and Australia to tame the blazes that have scorched an area the size of Rhode Island.

Some 560 wildfires were burning as of Friday, Gov. Gavin Newsom said, including two fire complexes that on Saturday grew to be the second and third largest wildfires in California history. The fires have killed at least six people, injured 33 people and firefighters, and destroyed more than 500 homes and other buildings. 

Many of the blazes were sparked by an unprecedented Lightning siege of nearly 12,000 strikes over a three-day period.

“These lightning strikes came the exact week that we were experiencing some of the hottest temperatures ever recorded in human history – 130-degree temperatures in the southern part of the state of California,” Newsom said. “These fires are stretching our resources, stretching our personnel.”

The Bay Area National Weather Service said Saturday that more lightning could be possible again this weekend, through Tuesday, bringing “the potential for new fire starts.”

California fires: This is how a lightning storm can start a wildfire

Here’s what we know.

Map: How many fires are burning in California right now?

Some 560 wildfires were burning as of Friday, with three major fire complexes – encompassing dozens of fires – carving their way through forest, canyon country and rural areas in northern and central California. 

A group of fires in Napa Valley, known as the L.N.U. Lightning Complex, was spreading through Napa, Sonoma, Lake, Yolo and Stanislaus counties. The fire has burned more than 468 square miles and is 15% contained, according to Cal Fire.

“Every single one of my counties is on fire,” California state Rep. Cecilia Aguiar-Curry said Friday. “Listen to what we’re saying. Evacuate. Don’t stick around.”

East of Silicon Valley, the S.C.U. Lightning Complex was burning in Santa Clara, Alameda, Contra Costa, San Joaquin and Stanislaus counties. The fire has burned nearly 430 square miles and is 10% contained.

The L.N.U. and S.C.U. fire complexes grew to be the state’s second and third largest wildfires ever on Saturday, trailing behind the 2018 Mendocino Complex Fire, which burned more than 700 square miles, according to Cal Fire.

Further west, a third complex – the C.Z.U. Lightning Complex in Santa Cruz and San Mateo counties – has burned more than 98 square miles and is 5% contained.

“We have wildfires burning … the size of the state of Rhode Island. The size of the state of Rhode Island,” Speaker Nancy Pelosi said Saturday. “It’s very, very sad … All of us solute our firefighters.”

Hundreds of trees burn at Big Basin Redwoods State Park

California’s oldest state park, Big Basin Redwoods, has been damaged by the fires, which have charred hundreds of massive ancient coast redwoods – some more than 1,000 years old.

The fires have also damaged the park’s headquarters, historic core and campgrounds, according to the California Department of Parks and Recreation. All campers and staff had been evacuated.

Dozens of other state parks, beaches and nature reserves have also been closed.

Yosemite National Park remains open, but multiple park gateway communities are under wildfire evacuation orders.

Where will the West’s next deadly wildfire strike? The risks are everywhere

How lightning storms started California wildfires

Many of the fires were caused by a mass of lightning strikes last week – sparks that lit a tinder box of vegetation left dry and crunchy by months of persistent heat and low humidity. Read more about how those conditions evolved here.

“We’ve definitely had lightning complex fires before,” said Rick Carhart, Cal Fire public information officer for Butte County. “The scope of this one, just the fact it’s so many fires in such a large area of the state … is an anomaly.”

This particular surge of lightning-caused fires has been one of the most noteworthy in a decade, said Scott Rowe, a meteorologist with the National Weather Service.

Newsom on Friday attributed the phenomenon to climate change.

“These lightning strikes, this unprecedented heat dome, these world record temperatures, unprecedented in human history – we’re experiencing more and more of that because of climate change, and as a consequence, these fires are more ferocious, and they’re moving at much more rapid speeds,” Newsom said.

Wildfires in Colorado, across western states

Fires were also burning in Colorado, Utah, Montana, Oregon, Idaho, Nevada, Arizona, Texas, New Mexico and Wyoming, according to the National Wildfire Coordinating Group on Saturday.

“The heat dome that we experienced over the course of last week has not only impacted the state of California – it’s impacted the entire western United States,” Newsom said. “As a consequence of that, our mutual aid that goes outside the state of California has also been stretched.”

On Friday, Gov. Jared Polis activated the Colorado National Guard to assist the State Emergency Operations Center and incident commanders fighting wildfires. Voluntary evacuations were underway in parts of the state.

What is the air quality and why don’t cloth face masks help?

Smoke from the fires is making the air quality in parts of California some of the worst in the world. And people in the area might not be able to smell the dangerous pollutants in the air.

Air quality experts measure the amount of fine particulate matter (PM 2.5) in the air. According to the U.S. Environmental Protection Agency, those particles come from a variety of sources, including fires. Smoke from fires can send large amounts of PM 2.5 into the air and over large areas.

“Whenever things burn there’s a mixture of gases and particles,” said University of California, San Francisco pulmonologist Dr. John Balmes, an expert on the respiratory and cardiovascular effects of air pollutants. “When you smell smoke, you are smelling the gases in the air, not PM 2.5 . . . They go hand-in-hand near the fire source, but the particulates travel in the upper atmosphere.”

It’s possible to have bad air — air high in PM 2.5 — without smelling gases.

Your coronavirus mask may not protect you, unless you have a mask designed to filter PM 2.5, like an N95. Those masks are scarce worldwide because of the pandemic. What residents really need are respirators.

Contributing: Doyle Rice, Elinor Aspegren, Wyatte Grantham-Philips, Joel Shannon, USA TODAY; Matt Brannon, Redding Record Searchlight; Brett McGinness and Amy Alonzo, Reno Gazette Journal; Kristin Scharkey, Palm Springs Desert Sun

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