The firefighter Jeremy Stoke was helping residents evacuate from the northern California city of Redding when the wildfire menacing their neighborhood arrived suddenly in an apocalyptic form: a riot of wind and flame known as a “firenado”.

As the firestorm ripped trees out of the ground and incinerated cars, Stoke radioed for help. But the potent combination of smoke and heat made it impossible to reach him, and his radio went silent. His colleagues found his body the next morning.

Stoke was one of five firefighters, in addition to a contract bulldozer operator and a mechanic, who have died fighting California wildfires in the past year, setting a deadly record even in a state where wildfires are a fact of life. According to the California Fire Foundation, this is the first time since record keeping began in 2000 that so many firefighters have died in so many fires and in so short a span of time. “For us, it’s been pretty shocking,” said Cliff Allen, who fought fires for 31 years before becoming president of Cal Fire Local 2881, a major state firefighters’ union.

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This summer’s cluster of tragedies is part of a sea change in a field that’s becoming increasingly demanding. As the climate shifts, California has been swept by “megafires” of unprecedented size and ferocity. The state’s fire season now lasts 78 days longer than it did 50 years ago, encompassing most of the year, from early spring until late December. “It used to be a 10,000-acre fire was a big fire,” said Gabriel Lauderdale, a firefighter in San Mateo county, south of San Francisco. But the Carr fire that killed Stoke has burned over 200,000 acres, and the Mendocino Complex fire 200km north of San Francisco, recently topped 400,000 acres, making it the largest in California’s history.

Firefighters are pushing themselves to their physical and emotional limits to battle these blazes, staying awake for days, sleeping in the dirt, working away from their homes for more than a month. They are doing so even as their colleagues die, and they are grappling with grief and a profound exhaustion that some in the field believe may have contributed to those deaths.

“I can’t recall a time where we were looking at three different memorial services within a two-week span,” Carroll Wills, a spokesman for the California Professional Firefighters, said of the state’s deadly summer. “The men and women on the frontlines, they’re exhausted, they’re hurting,” he added. “Our resources are being pushed to the limit. It’s going to exact a price.”

Facebook Twitter Pinterest A flag at half mast in front of a burned firehouse outside of Redding. The Carr fire destroyed large swaths of the city and surrounding area. Photograph: Brian L Frank/The Guardian

At the height of California’s firefighting efforts this summer, there were 14,000 firefighters from 17 states, as well as Australia and New Zealand, deployed in the field. Even at the best of times, theirs is an all-consuming job.

So-called “wildland” firefighting bears little resemblance to its urban counterpart. With smaller wildfires, firefighters stationed on safe zones of land that have already burned spray water at the flames, sometimes dragging hundreds of feet of hose over rough terrain. For larger fires, indirect tactics are necessary. Handcrews work with tools and other firefighters operating bulldozers to chop thick woodland down to bare soil and create firebreaks, while their colleagues wet down roads or set backfires, small blazes that impede the momentum of rampaging flames by limiting their fuel.

The work is relentlessly hot, smoky and tiring. Firefighters wear hoods, jackets, pants, bootsand goggles to protect themselves and often hike long distances wearing heavy packs in temperatures exceeding 40C (104F). “You’re pretty much always thirsty,” Lauderdale said. “Even when you feel like you can’t drink any more water, you’re still thirsty because you’re sweating so much.”

Firefighters can lose about 6kg of water weight during a shift. Co-workers tease each other about the “tie-dye” salt stains left on their shirts, and chafing is a major issue that calls for religious application of baby powder. At the end of a shift, “I often have marks on my shoulders from where my pack is and on my hips from where my belt was,” Lauderdale said.

The men and women on the frontlines, they’re exhausted, they’re hurting Carroll Wills

Each firefighter has his or her own set of survival hacks – like insoles for aching feet and moleskin to guard against so-called “White’s bites”, blisters where White’s brand firefighting boots flex against the top of the foot. They are loyal to certain snacks; Allen likes to tuck M&Ms in his pack because the hard shells don’t melt as much as other candy might near flames.

The resounding consensus, however, is that any discomfort is worth being able to help in such a specific, concrete way. “There’s instant gratification to it: you put the cold blue stuff on the hot red stuff, next thing you know it’s out,” Allen said.

Facebook Twitter Pinterest Firefighters like Gabe Lauderdale are dealing with increasingly large and dangerous fires. Photograph: Brian L Frank/The Guardian

Firefighters have always risked their lives on the job. Along with those on the fire line, pilots, mechanics and other support staff have died fighting fires in the last 20 years – including aerial incidents in 2005, 2006, and 2008 involving multiple pilots. Still, there have never before been so many deaths from so many separate incidents so quickly.

Now the state’s fires are more severe than ever. Some 129m trees died during California’s most recent stretch of extreme drought. Dead vegetation speeds the expansion of a blaze, which then kicks up winds that can change a fire’s direction without warning and carry live embers as far as a mile – spurring a line of flames that can grow alarmingly fast.

Those fast-moving flames killed Stoke as he evacuated Redding residents. They also overwhelmed Cory Iverson, who was surrounded by newly-sparked “spot fires” in southern California. Braden Varney fell down a precipitous incline while driving his bulldozer over treacherous terrain at the Ferguson fire in Yosemite. A dead tree struck Brian Hughes while he fought the same fire two weeks later. Don Ray Smith was clearing brush from the path of the Carr fire when flames overtook his bulldozer. The mechanic Andrew Brake died in a single-vehicle accident on his way to work nearby. Most recently, Matthew Burchett was killed by falling debris after a fire retardant drop at the Mendocino Complex fire.

A Cal Fire spokesperson emphasized that each death took place in a unique situation with complicated circumstances. But Allen connects the recent spate of deaths both to this new breed of extreme fires and to the exhaustion that results from fighting them. “Guys have been out for weeks on end, working non-stop,” he said. “That’s definitely going to wear on folks, and you’re not going to be as attentive.”

Facebook Twitter Pinterest A burned firehouse outside of Redding. The last year has been particularly deadly for firefighters. Photograph: Brian L Frank/The Guardian

On the fire line, firefighters are supposed to be on shift for a maximum of 24 hours, then get 24 hours off, but that has changed. Now, during the early days of out-of-control fires like those this year in Redding and last year in wine country, firefighters may have to work days without a break as they wait for relief from teams that are already fighting fires elsewhere.

That means taking rest where they can get it. During July’s Carr fire, a viral Instagram photo showed a group of firefighters in full yellow and black regalia, curled up asleep on the charred ground, their tools at their sides.

“It shouldn’t be, it’s not supposed to be typical,” said Lauderdale, but “we see it quite often now”. Lauderdale’s longest stint awake on the job was 72 hours. At that point, he said, the world got a little blurry, and one’s sense of time disintegrates. “You can’t remember when things happen. Did an hour go by or did 15 minutes go by?” he said. He ultimately fell asleep during a quieter moment, only waking up when a colleague found him slumped over his hose. Other nights, he has slept in his engine or curled up on his jacket on the rocky ground.

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More time near the flames also means higher risk of heat exhaustion, so teams watch carefully for any symptoms – profuse sweating, cramps, nausea. Lauderdale has been there. “You feel like your heart’s beating out of your chest,” he said. “You can’t seem to cool down. There’s been times I’ve had to hike back down to the engine, take some ice out of the ice chest, and put it down my shirt.”

These difficulties mount when strung together. Resources stretched thin across the state mean many firefighters are spending far longer than they are meant to away from home. On a normal schedule, firefighters committed to big fires work for two- or three-week stints – 24 hours on, 24 hours off – and then get one or two days to rest. “The problem is that with high demands, that doesn’t always happen,” Allen said. The longest period he was away from home during his career was 32 days; this year firefighters have been in the field for between 30 and 40 days “pretty regularly”, he said.

Facebook Twitter Pinterest The memorial for firefighter Jeremy Stoke, who was killed by the largest ‘fire tornado’ to ever touch down in California during the Carr fire. Photograph: Brian L Frank/The Guardian

A firefighter faces death frequently; Allen had to pause to count the number of firefighters he knew who had died in the line of duty before settling on four. Among the most painful of those was his friend Matt Will, at a fire on the California coast in 2007. Will was driving his bulldozer over rolling and uneven terrain when the ground gave way. Allen was above the scene, in a helicopter dropping water, when he heard there had been an accident. From the air, he watched as other firefighters tried to get Will out of the cab. They did – but not soon enough.

In the days after Will’s accident, Allen remembers feeling overcome by a sense of weakness so profound “it seemed difficult to pick up a sheet of paper”. He spent hours playing the scene over in his head, obsessing about how he might have changed its outcome. That weakness slowly transformed into anger, then eventually into what he called a “tremendous sense of loss”.

Fire departments are increasingly recognizing the impact of trauma and exhaustion on firefighters’ wellbeing and putting more emphasis on self-care and emotional support. That includes more generous vacation policies, therapy dogs, and so-called critical incident stress management meetings, during which a team of therapists, chaplains and peer supporters give advice on topics like how to get enough rest or how to talk with loved ones about a colleague’s death.

Perhaps most importantly, these meetings are designed to create opportunities for firefighters to talk about their feelings. It is an essential innovation in a job with no room for emotion or distraction.

“A professional can’t feel out there,” said Nancy Bohl-Penrod, who helps run critical incident meetings in California. “They’ve gotta get their job done. They stuff it, and they do it very well, and then when they get into the group you’ll see the reactions. It’s almost like a release valve.”

Because of the necessity of compartmentalizing on the job, “a lot of times first responders feel like they’re the only ones going through the thought process and emotions”, she said. “When they’re together, they get to hear, ‘Oh, that happened to me too,’ and, ‘Yeah, I couldn’t sleep. My partner and I started fighting too.’”

Allen found the meeting he attended around Will’s death to be difficult but powerful. “You see all these grown men crying, spilling their guts,” he said. But “being with my crew and getting those emotions out helped”.

Facebook Twitter Pinterest The Carr fire tore through Redding, destroying large swaths of the city and killing two firefighters. Photograph: Brian L Frank/The Guardian

Lauderdale grew up in Redding and knew Stoke, the firefighter who died while evacuating residents, as the teacher of an automobile extrication course at his fire academy and then as a friend.

One of the worst things about grieving for a fellow firefighter, he said, is the feeling of helplessness. “Firefighters want to help. You’re rushing in when everybody is rushing out. To have a situation where you can’t do anything, that is really tough.” He sighed. “The thing I kept dwelling on is: what if he had gotten up that day and lost his keys? What if he’d been one minute earlier or one minute later walking out the door?”

He remembers Stoke as a well-liked jokester with an infectious, raspy laugh; a “larger than life” fan of the San Francisco Giants and heavy metal music with full-sleeve tattoos; and a patient teacher who took time to explain complicated concepts and never condescended.

Lauderdale heard about Stoke’s death when he arrived in Redding from fighting another fire and immediately broke down. “For several days afterward, I had that feeling right before you start to cry, that feeling in your throat below your chest,” he said. Lauderdale spent one of those days doing yard work and letting the tears come. To manage his grief, he has been leaning on his friends and, in a new development, his wife – a skill he says the critical incident meetings helped him develop.

Last Wednesday, after nearly eight weeks away – and three much-needed days off – he finally finished work on the Carr fire and reported to his home station outside San Francisco. It’s hard to say what will happen next. But, like many of his colleagues, he’s acutely aware that it’s only August. Last year, there were firefighters working on Christmas Day.