California wildfires burn at least 600,000 acres in one week, killing 5 and degrading air quality

Evacuations surged Thursday and Thursday night as authorities worried that high heat and gusty winds could cause the fires to spread rapidly. By midday, several of the major fires had more than doubled in size, in some cases jumping across major highways, as crews struggled to contain the blazes. By Friday morning, the largest blaze, known as the LNU Lightning Complex, had charred 219,000 acres, having expanded by 4,000 acres overnight amid cooler conditions.

Another blaze, known as the CZU Lightning Fire, has forced the evacuation of more than 64,000 people, according to Cal Fire. Officials said some may not be able to return to their homes for weeks. 

The fires have been blamed for at least five deaths.

Many of the fires began days ago, as a heat wave and an unusual series of storms produced more than 20,000 lightning strikes. The resulting fires - and "complexes" of many small fires - have merged into major conflagrations in many parts of the state.

Officials have urged everyone in California to prepare a bag filled with a change of clothes and necessities, and to be ready to evacuate their homes on a moment's notice.

This is just the beginning of the state's wildfire season, something that has been a constant threat during the past four years of record-setting blazes, both for their breadth and their lethality. Despite the familiarity, the current fires and their speed and thick smoke have presented a new terror amid a global pandemic - poor air quality, concerns about evacuating masses of people to crowded shelters, and concerns that some might not heed the warnings.

And the fires, spread across hundreds of miles, have presented an overwhelming challenge to the crews trying to battle them as California has issued a nationwide call for help.

Arjun Mendiratta has lived in La Honda, Calif., for two years, in a small community surrounded by tall trees south of San Francisco in the Santa Cruz mountains. He and his wife packed their 1½-year-old son in the car Wednesday night and drove to Half Moon Bay, a town on the coast, where they stayed in a hotel for the night. Already packed, they decided to leave their home after receiving an evacuation warning message as fires approached; they did not want to wait for a full evacuation order and risk getting caught in traffic.

"We thought, 'Let's just go while we can,' " Mendiratta said, noting that not all his neighbors plan on leaving, hoping better weather will come before the flames do.

In San Mateo and Santa Cruz counties, where La Honda is located, about 48,000 people were ordered to evacuate because of a fire threatening communities there, part of the CZU Lightning Complex. The blaze had already burned 50 structures, fire officials reported. On Thursday evening, the University of California Santa-Cruz was under a mandatory evacuation and had declared a state of emergency.

Tens of thousands of people have been asked to evacuate, having to make difficult decisions about where to go. In the past they might have stayed with friends or family, but now they need to calculate the risk of exposure to the novel coronavirus.

And wherever people go, they are likely to face other hardships. California has been enduring a record-breaking heat wave that has prompted rolling blackouts because of high electricity demands for air conditioning and other uses. And most of the area is experiencing severe or moderate drought.

The largest of the lightning-related fires was north of San Francisco, covering Napa and Sonoma counties. On Thursday, that mass of fires, called the LNU Lightning Complex, had grown to 219,000 acres and was 0 percent contained, according to CalFire. Approximately 30,000 structures were at risk of burning and 480 had been destroyed.

The blaze near Vacaville, known as the Hennessey Fire and part of the LNU Lightning Complex, has been one of the most destructive, burning down homes and claiming the life of a PG&E worker who was assisting first responders. This same blaze burned down the La Borgata Winery and Distillery in Vacaville. Mandatory evacuations remained in effect for the north part of the city Thursday.

Cal Fire reported three additional civilian fatalities associated with the LNU Lightning Complex Thursday evening.

"The public needs to be prepared and have a plan and have a go bag," said Brice Bennett, public information officer for CalFire, the state's firefighting agency. "This is showing us we can have wildfires anywhere."

CalFire is at normal staffing levels, with approximately 11,000 firefighters working Thursday, Bennett said. The state has asked for 375 fire engines from out of state for help, in part to give current units a chance to rest.

In central California, a pilot on a firefighting flight near Fresno died when his helicopter crashed, and the National Transportation Safety Board is investigating.

California has trained volunteer inmates to fight wildfires as part of its Conservation Camp Program, which was started during World War II. The inmates train and live in camps across the state, but because of the coronavirus the number of available volunteers is down. There are usually 2,200 inmates qualified to fight fires on the front lines in the camps, but now the California Department of Corrections and Rehabilitation says there are just 1,659.

"The decrease in conservation camp population is attributed to a combination of expedited and standard releases," said Aaron Francis, a spokesperson for CDCR.

CalFire says it anticipated the impacts of the coronavirus and hired additional firefighters ahead of the wildfire season.

The effects of the coronavirus and the wildfires are tangled in other ways. Smoke from the fires is a complicating factor, as it and the virus can attack the lungs and could have a greater impact on people with certain preexisting health conditions. The massive blazes are sending plumes of smoke and ash into the skies surrounding populated areas, including San Francisco, fouling air quality for hundreds of miles.

"We're very worried about that combination this fire season, about wildfire smoke exposures and a raging pandemic," John Balmes, a medical professor at the University of California San Francisco and a member of the California Air Resources Board.

Bay Area residents for months have been told that outdoor spaces are safer than being indoors during the coronavirus outbreak. Now, they're being asked to stay indoors if possible.

The cloth masks that have now become habit for many Californians when they venture outside are largely ineffective against the tiny smoke particles filling the air, Balmes said. Balmes and other UCSF doctors recommend finding N95 masks with vents, since they're not in demand by health-care workers, or even trying used N95 masks.

He recommends that people shelter in place, staying at home with their windows closed and ventilation systems set to recirculate air. Staying indoors with windows closed is a big ask during a heat wave, especially in areas such as San Francisco, where many people do not have air conditioning.

Here are key figures on the latest blazes:

The LNU Lightning Complex in Sonoma, Lake, Napa and Solano counties has burned 219,000 acres, up from 46,000 acres Wednesday, and is 0% contained. This complex includes the Hennessey Fire, which has charred 192,000 acres in Napa County. It has destroyed 480 structures and threatens 30,000 more.

The CZU August Lightning Complex in Santa Cruz and San Mateo counties has burned 50,000 acres, up from 10,000 acres Wednesday, and is 0% contained. It has burned 50 structures and threatens nearly 21,000 more. About 48,000 people have been evacuated.

The SCU Lightning Complex of about 20 fires, affecting locations in Santa Clara, Alameda, Contra Costa, San Joaquin and Stanislaus counties, has consumed more than 157,475 acres, up from 85,000 acres Wednesday, and is 5% contained.

The River Fire in Monterey County has consumed more than 33,000 acres, up from 10,000 acres Wednesday, and is 7% contained.

Due to increasing humidity and generally light winds, favorable weather conditions for fire spread are not expected Friday into the weekend. However, the National Weather Service office in San Francisco cautioned when sea breezes move inland, the "sudden increase in winds may push the fires during the late afternoon to early evening, bringing brief but potentially erratic and dangerous growth."

Late in the weekend, the forecast office in San Francisco wrote, Tropical Storm Genevieve, near the Baja Peninsula, could release a pulse of moisture and instability to increase the potential for more lightning "that may lead to further ignitions." Temperatures are also expected to increase during the weekend as well. 

Smoke will remain a persistent issue because of the ongoing fires, "so air quality will be a real problem through at least the end of the week," the Sacramento office wrote.

The California wildfires, along with other blazes in the West, have sent a blanket of smoke across at least 10 states and southwestern Canada, with tendrils of smoke extending over the Pacific Ocean as well. Air quality alerts are in effect for parts of California, where the tiny particles in the dense smoke will be capable of aggravating respiratory conditions and worsening preexisting health conditions.

The fires stem from an unusual confluence of extreme weather events, set against the backdrop of human-caused global climate change, which is causing more frequent and severe heat waves in the region as well as larger wildfires across the West.

Appearing via video from a forest near Watsonville, Calif. Gov. Gavin Newsom, D, attributed the barrage of blazes to climate change. 

"If you are in denial about climate change, come to California," he said.

The immediate trigger of most of the more than two dozen large fires burning in the Bay Area was an unusual August thunderstorm outbreak, which lit up the night skies above San Francisco on Sunday and Monday and moved inland, where lightning discharges struck trees and grasses at a time of year when vegetation is at its driest.

Between midnight Saturday and midnight Wednesday, there were 20,203 cloud-to-ground strikes in California, according to Chris Vagasky of Vaisala, which operates the National Lightning Detection Network. The total number of lightning discharges, which includes lightning that jumped from cloud to cloud without hitting the ground, was equivalent to 11% of California's average annual lightning activity, he said via a message on Twitter.

The storms were the result of moisture moving north from former Tropical Storm Fausto near the Baja Peninsula and the sizzling heat across the state.

The long-lasting and intense heat wave has played a key role in these blazes. Multiple monthly heat records have been set in the past 10 days, including in Death Valley, Calif., where one of the hottest temperatures on Earth, a high of 130 degrees Sunday, was recorded.

One measure of fire risk is known as the evaporative demand drought index, or EDDI. It measures the "thirst" of the atmosphere and can help predict fire risk. In part because of the heat's ability to speed up evaporation, the EDDI in Central and Northern California preceding these fires soared to record levels, indicating a high fire risk.