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An image of the Mosquito Fire captured by wildfire cameras. 

Air quality index readings around the perimeter of the Mosquito Fire were reaching hazardous levels. 

The Mosquito Fire burning in Placer and El Dorado counties torched buildings in Volcanoville. California’s heat wave is waning, but the risk of new fires starting and spreading quickly will persist. Gov. Gavin Newsom declared a state of emergency in Placer and El Dorado counties due to the Mosquito Fire and in Riverside County due to the Fairview Fire.

We’ll be reporting on all the latest news on the Mosquito Fire and other major California wildfires throughout the day.

Pacific Gas & Electric Co. personnel found no immediate evidence of problems, such as vegetation contact or damage, with power equipment on a steel transmission pole near the origin of the Mosquito Fire, a utility spokesperson said.

Federal firefighting personnel have cordoned off the ten-year-old pole. PG&E systems detected an electrical fault on the pole around the time the fire started.

Chris Vestal, a spokesman with the Mosquito Fire incident, said equipment might be cordoned off for several reasons, such as ensuring crew safety, preserving potential evidence or to protect infrastructure.

He declined to say whether investigators suspect power equipment started the fire.

The transmission line serves the Placer County Water Agency’s power plant on the Oxbow Reservoir. It had been inspected within the last five months, according to PG&E.

The Tahoe National Forest is leading the investigation into the fire's cause, according to Vestal.

Weather readings clocked wind gusts at 4 mph when the Mosquito fire was first reported at 6:22 p.m. Tuesday. The temperature was 97 degrees at a weather gauge near Foresthill Union Elementary school, down from an earlier high of 101.

Placer County firefighters were already battling a new fire that started earlier Tuesday and several miles north. The Hill Fire reached about 11 acres and led authorities to evacuate people out of the Giant Gap, Big Reservoir, Shirttail Creek and Morning Star Lake campgrounds.

Berkeley Forests staff said on Friday that they have confirmed with on-the-ground fire personnel that the Mosquito Fire is burning within the boundaries of Blodgett Forest Research Station.

All Blodgett Forest personnel were evacuated and marked safe before the fire entered the property. “Although the fire has not yet burned in this area, it will likely reach this portion of the property in the coming day,” the agency said in a bulletin. “Fire personnel have indicated that structure protection is their priority at this time.”

Ash and particulate matter coming off the fast-moving Mosquito fire has turned air quality hazardous and painted skies a hazy orange.

AlertWildfire cameras show shades of orange, pink and gray covering the North Tahoe region and closer to where the wildfire is burning in Placer and El Dorado counties.

An Alertwildfire camera shows an eerily orange sky north of Auburn, Calif. on September 9, 2022.

As a result of the extreme fire behavior small particles of dust, soot and ash are capitulated into the air. In the regions surrounding the blaze air quality index levels are more than 300, which can trigger serious health effects.

The extreme scene comes two years after dozens of lightning-sparked wildfires burned throughout the state, skies turned an apocalyptic-orange in places far from the flames, like San Francisco.

Hurricane Kay remnants are likely to bring tropical-like humidity to the Bay Area over the weekend, with a possibility of some rain, but in Southern California the tropical system is kicking up extreme weather.

Kay is moving northward off the coast of the Baja California peninsula and has already brought upwards of two-tenths of an inch of rain to San Diego County’s Laguna Mountains and the Cleveland National Forest. There are risks for torrential downpours and flash flooding in the coming days for the canyon passes and roadways near cities like Murrieta and Escondido.

California State Route 193, which runs through Placer and El Dorado counties, has been closed due to the Mosquito Fire, according to an update from Caltrans. The expected reopening time for the highway, which is located inside the mandatory evacuation area, is unknown at this time. “Please avoid the area if possible to allow emergency crews access,” the agency said.

The Mosquito Fire burning in Placer and El Dorado counties grew to 29,585 acres in size late Friday morning, according to information posted by the U.S. Forest Service.

The grid could see up to a 60% reduction in solar production — about 5,000 to 6,000 megawatts — due to wildfire smoke and cloud cover Friday, grid operator COO Mark Rothleder said in a Friday morning press call.

On Thursday, the grid saw a 30% reduction in solar production -- about 3,000 to 4,000 megawatts -- because of cloud cover and smoke, Rothleder said. Demand peaked Thursday around 48,300 megawatts, significantly lower than the 50,000+ megawatts of demand seen in prior days of the heat wave.

Demand is expected to peak Friday at 46,118 megawatts, with the grid having current capacity of 54,739 megawatts, as of 10:50 a.m.

As the Mosquito Fire sparked and then exploded into a massive inferno in California’s Gold Country foothills Wednesday, Mary Garbe was celebrating her 68th birthday in her Forestville mobile home, the fire was heavy on her mind.

But when local Sheriff deputies arrived the next day urging them to evacuate, she told her husband, Ken, 72, she wouldn’t go.

Their seven cats, including five kittens, still hadn’t returned home. She didn’t want to leave them behind.

“I’m not going,” she told her husband, Ken. “They’re going to have to handcuff me.”

By Friday morning, the smoke grew heavier, the air choking them as the temperatures pushing into triple digits and her husband convinced her to leave.

“I just kept yakking at her,” he said. They left their front door open, in hopes the cats would return, grabbed their important documents, a safe filled with the last of their money and headed to the Baptist church in Auburn which had opened as an evacuation center, joining thousands of residents forced to flee their homes.

Mary wondered about her cats.

“I miss them,” she said.

Ken worried about the home.

“We’re going to be homeless if the trailer burns out, and 72 is too old to be homeless,” her husband said.

Gov. Gavin Newsom today said California has received a Fire Management Assistance Grant from the Federal Emergency Management Agency to support local agencies as they battle the Mosquito Fire. The grants “enable local, state and tribal agencies to apply for 75-percent reimbursement of their eligible fire suppression costs,” Newsom’s office said.

Smoke from the Mosquito Fire has made it over to the Bay Area, bringing hazy skies with it. 

“Today it’ll start to disperse out a little bit, but tonight we’ll get higher concentrations of smoke coming back into the Bay Area,” said National Weather Service meteorologist Sarah McCorkle.

Smoke from fires across the state pushes into the Bay Area today and tomorrow, but most of the smoke is expected to be elevated. Pay attention to air quality alerts from local air quality districts and get the latest information at https://t.co/WQ0XLAmi67. pic.twitter.com/QJqg08kuoE

Tropical Storm Kay in southern California has changed wind patterns to east-west, carrying the smoke from Mosquito Fire to the Bay Area, McCorkle said. The smoke could start veering north Saturday, McCorkle said. 

Most of the smoke is at elevated levels, McCorkle said. Currently, air quality in the Bay Area ranges from “Good” to “Moderate” on the Air Quality Index, according to AirNow, a service operated by the Environmental Protection Agency.

The Mosquito Fire is causing “terrible, no good, very bad air quality” across California’s Central Valley, according to Jeff Beamish, a meteorologist at Sonoma Tech. As of 9:45 am, he said that most regulatory and retail air monitors reported an unhealthy air quality index score from the region east of downtown Sacramento to Lake Tahoe. Cal Fire officials said they have been unable to accurately map the fire perimeter due to smoke conditions 

El Dorado County reports 2,000 structures imminently threatened by the Mosquito Fire, with another 11,500 in warning zones, with more than 17,000 residents affected. The fire continues to be fast-moving, forcing one evacuation shelter, Cool Community Church, to close after it fell into the evacuation warning zone.

Flames as high as 100 feet shot through the trees as the Mosquito Fire tore through Foresthill, according to an update from the Placer Sheriff . “Fire crews worked hard to knock them down,” the office said in a tweet.

The fire has now expanded to 14,250 acres and is 0% contained, Cal Fire said. The fire has quadrupled in size and spread across El Dorado and Placer counties. “Assigned personnel continued to improve existing control line and build new control lines, and also assessed and prepared structures threatened by the fire,” the agency said in an update Friday. “The fire is burning in extremely difficult terrain including steep canyons where directly attacking the fire can be difficult.” 

Air quality index levels are fast-approaching 300 and above around the Mosquito Fire perimeter Friday morning, while more scattered 150-200 (unhealthy) levels are being measured all along the Northern Sierra. Prevailing winds at the higher levels of the atmosphere (15-20,000 feet) will shift and become easterly winds this afternoon thanks to the remnants of Kay to our south. This is important because the core of the pyrocumulus clouds fanning smoke from the fire are around that height. So we can expect some of the particulates from the smoke to waft into the Sacramento Valley and parts of the Bay Area, decreasing air quality further on Friday.

The Chronicle's Air Quality map showed unhealthy and very unhealthy air ringing Lake Tahoe as a result of the Mosquito Fire. 

The Chronicle’s Air Quality map showed unhealthy — and in some places, very unhealthy — air quality around Lake Tahoe, likely due to the smoke billowing off the Mosquito Fire.

Patches of unhealthy or very unhealthy air were recorded across a vast swath of Northern California northeast of Sacramento.  

Images captured by wildfire cameras showed hellish plumes of smoke created by the fast-moving Mosquito Fire. Persistent hot, dry conditions were expected to help the fire grow at a rapid pace overnight. 

Gov. Gavin Newsom declared a state of emergency in Placer and El Dorado counties due to the Mosquito Fire and in Riverside County due to the Fairview Fire on Thursday afternoon. Both wildfires are threatening multiple communities and have forced the evacuation of tens of thousands of residents. The declaration frees up state resources to help residents affected by the fire and to help firefighters battle the fires.

Dominic Fracassa is an assistant metro editor overseeing breaking news and criminal justice in San Francisco. He previously covered San Francisco City Hall as a staff writer.

Gerry Díaz is The San Francisco Chronicle's first ever Newsroom Meteorologist.

He previously served as a meteorologist for the National Weather Service Bay Area, working from the agency's Monterey office. In that position he led an initiative aimed at increasing outreach to Spanish speaking communities during extreme weather events.

Most recently he worked as a meteorology specialist for utility Southern California Edison.

Díaz enjoys hiking through California's national parks and shooting panoramic photography, including of the Central Coast.

Jill Tucker has covered education in California for 22 years, writing stories that range from issues facing Bay Area school districts to broader national policy debates. Her work has generated changes to state law and spurred political and community action to address local needs.

She is a frequent guest on KQED's "Newroom" television show and "Forum" radio show. A Bay Area native, Jill earned a master's degree in journalism at the University of Colorado, Boulder and a bachelor's degree from the UC Santa Barbara. In between, she spent two years as a Peace Corps volunteer teaching English in Cape Verde, West Africa.

Aidin Vaziri is a staff writer at The San Francisco Chronicle.

Claire Hao is A Hearst Reporting Fellow who joined the San Francisco Chronicle in 2022. She is a recent graduate of the University of Michigan, where she forayed into journalism at the student newspaper. Since then, she has interned on the news desks of Bloomberg Law and The Chicago Tribune as well as on the editorial board of The Washington Post. She was also the 2021 editor-in-chief of her college paper The Michigan Daily.

Having lived in Michigan for most of her life, Claire is really excited to begin her professional career by exploring two different cities. In her free time, Claire enjoys reading, writing, running and playing the guitar.

Kate Galbraith is The Chronicle's Climate Editor, overseeing energy and environment coverage. Previously she edited COVID and business coverage. Kate has also worked for the Texas Tribune, CALmatters, The New York Times and the Economist. A native of Washington, DC, Kate began her writing career at Let's Go and Lonely Planet travel guides. She is co-author of The Great Texas Wind Rush, a book about how the oil and gas state came to lead the nation in wind power.

Sarah Ravani covers Oakland and the East Bay at The San Francisco Chronicle. She joined The Chronicle in 2016 after graduating from Columbia University's Graduate School of Journalism. Previously, she covered breaking news and crime for The Chronicle. She has provided coverage on wildfires, mass shootings, the fatal shooting of police officers and massive floods in the North Bay.

Julie Johnson covers the changing climate, sea level rise and strategies to stem California's wildfire crisis. Before joining The Chronicle, she spent 11 years as a staff writer at the Santa Rosa Press Democrat, where she had a leading role on the breaking news team awarded the 2018 Pulitzer for coverage of the 2017 Wine Country fires. Julie has covered murderous pot deals, police corruption and marijuana's rocky path from a black-market trade to a legitimate industry.