California is in the midst of perhaps the most challenging fire year in its history, with yet another dangerous set of weather conditions developing in a state that endured unprecedented heat and explosive blazes over the holiday weekend.

More than 2.2 million acres have burned so far in 2020, surpassing 2018 for the most acres burned annually in the modern record. Three of the state’s four largest wildfires have occurred in the past three weeks — all exceeding 300,000 acres and not yet fully contained. The Creek Fire in Sierra National Forest, where rescues of trapped hikers and campers are still underway, has ballooned to 143,929 acres in two days, with 0 percent containment.

But the wildfire threat is not limited to California.

On Monday, blazes broke out amid strong winds and dry air in Washington state. Some of the blazes spread dozens of miles in a single day. Most of the small town of Malden, Wash., about 35 miles south-southwest of Spokane, was destroyed in one fast-moving blaze.

In western Oregon, wildfires grew in number and severity throughout the day Tuesday, pouring smoke plumes out to sea and turning skies in some areas an unsettling orange hue. One fire reportedly destroyed an estimated 80 to 100 structures Monday night in Blue River, located east of Eugene along the McKenzie River in the Willamette National Forest. "We should expect loss of life from this fire,” the Lane County administrator told an emergency session of the Lane County Board of Commissioners on Tuesday morning.

Wildfire smoke mixed with airborne dust to create hazardous driving conditions and dangerously poor air quality in the state, with widespread road closures in central and eastern Washington as well. Hazardous air quality as a result of wildfire smoke has spread across the West, though it will be most concentrated along the West Coast on Tuesday.

On Tuesday, red-flag warnings for dangerous fire weather stretched along the entire West Coast from the U.S. border with Mexico to Canada, including much of California and Nevada, western Oregon and Washington, along with western Arizona and southern Utah. Strong winds are buffeting areas in and around Seattle and Portland, Ore., with wildfire concerns in both areas. In some places, winds have been strong enough to knock out power. More than 100,000 customers were without electricity in both Oregon and Washington amid high winds Tuesday morning.

The National Weather Service’s Storm Prediction Center wrote that the fire danger was particularly severe in parts of western Oregon and far southwestern Washington state, where it described “extremely critical” conditions. There, the combination of wind gusts over 60 mph, low humidity, high temperatures and a parched land surface “all suggest continued potential for rapidly moving fire fronts and extreme fire behavior,” the center wrote.

California’s ‘extreme fire behavior’

The acreage burned in California, while astounding, does not tell the whole story. Fires have been burning in unusual ways this summer, with fire behavior that eludes firefighters’ control. That has allowed them to grow so big, so quickly, without much wind to push them along. Fueled by record-setting temperatures, up to 120 degrees even near the coast, they have spawned towering columns of smoke and ash, forming their own thunderstorms and even fire tornadoes.

But the heart of the fire season is still ahead: Fast-spreading blazes are most common in autumn, when fierce “offshore” winds blow from inland areas toward the coast.

Those winds have arrived this week, unusually early, on the heels of a record-shattering heat wave. Red-flag warnings are in place for much of Northern and Southern California, as well as the Sierra Nevada mountains and foothills, as critical fire weather migrates from north to south. The winds threaten to push existing fires into communities, particularly those in the Bay Area and in Los Angeles, San Bernardino and San Diego counties, which are burning near populated areas.

These winds will transport extremely dry air, with humidity measured in the single digits. This combined with the desiccated vegetation following the heat wave will create rarely encountered wildfire risks.

The California utility Pacific Gas and Electric — whose power lines sparked the state’s deadliest wildfire on record, which wiped out the town of Paradise in 2018 — has begun to implement preemptive power cuts that could affect 22 counties across the state.

In the Los Angeles area, the biggest immediate fire weather concern is related to the Bobcat Fire, burning in the San Gabriel Mountains just north of Azusa. Forecasters and firefighters are concerned the Santa Ana winds will cause the fire to burn down canyons to nearby foothill communities Tuesday and Wednesday.

The U.S. Forest Service has taken the unusual step of closing several national forests in California because of the extreme fire danger, which puts vast swaths of the state off limits to campers, hikers and other users. Dry, gusty offshore winds are expected in the San Francisco Bay area Tuesday, with a red-flag warning through Wednesday morning.

“Needless to say … following a heat wave this set up is not good for fire weather,” the NWS forecast office in San Francisco stated in an online forecast discussion. The offshore wind event is taking place as the state’s second-, third- and fourth-largest wildfires are still burning, along with a smattering of other blazes, such as the Creek Fire, that ignited and exploded in size this weekend.

The state is just at the beginning of what could be a long offshore wind season, with forecasters expecting warm and dry weather in the months ahead.

“It’s hard to come up with a scenario that is higher risk,” said Noah Diffenbaugh, a professor and climate scientist at Stanford University.

“We haven’t gone into a wind event in California with this many large fires burning,” he said. “Just from that perspective, we are in uncharted territory.”

Climate change has its ‘thumb on the scale’ of extreme fire

This summer’s fires reflect explosively dry conditions, the result of the very dry winter in the northern third of the state, a warm spring that led to rapid mountain snowmelt, and two record-breaking heat waves in mid-August and early September, among other factors.

According to Diffenbaugh, global warming has its “thumb on the scale” of wildfire — pushing it to extremes as rising temperatures make fuels drier.

The heat is acting on many time scales, from a general rise in temperature to acute heat waves such as those immediately preceding the most recent spate of enormous fires.

“Heat waves are breaking records everywhere, and as temperatures soar, so does the speed at which the soil and fuels dry,” Leila Carvalho, a professor of meteorology and climate science at the University of California at Santa Barbara, said in an email.

“What has changed in summer is the frequency and intensity of heat waves, a climatic response to an anthropogenic increase in greenhouse gases that has been predicted [by] climate models [for decades],” she said.

There has also been a broad and statistically significant year-round warming in California since 1895, especially in late summer and early fall, just when the state is hitting peak dryness and is about to enter its offshore wind season.

Documented increase in dangerous fire days

California’s most destructive and deadly fires have happened in autumn, on the days that dry winds whip across a landscape that hasn’t seen rain in months.

“Rapidly spreading wildfires are driven by strong gusty winds, and they can be larger, costly and cause many casualties,” Carvalho said.

It is now apparent that Californians must contend with these high-risk days more often.

“Extreme fire weather is becoming more frequent with climate change, and will continue to do so into the future,” Michael Goss, a postdoctoral research fellow in earth system science at Stanford University, said in an email.

Goss is the lead author, along with Diffenbaugh and other climate and wildfire experts, of a study recently published in the journal Environmental Research Letters. It shows that the state’s most dangerous autumn fire weather days, which are more likely to have big, hard-to-control wildfires, have more than doubled in frequency in the past four decades.

They define these risky days as those registering the highest (greater than the 95th percentile) readings of the Fire Weather Index (FWI), a fire danger metric that combines a number of weather measurements, including wind, temperature and humidity, as well as estimates of plant flammability and drought.

Higher values of the index have been associated with more-intense wildfires, as well as more land area burned.

The trend in the FWI coincides with a similar trend in temperature, which has increased by about one degree Celsius since 1980, and is probably the main driver here.

“The primary pathway by which global warming affects extreme fire weather is through temperature,” Diffenbaugh said.

But autumn precipitation has also declined in the same time period. In the past several years, in particular, there simply has not been enough rain in October and November to halt, or at least tame, destructive fire seasons.

The potential for dangerous fire weather is therefore headed upward across many ecosystems statewide. That trend is expected to continue, although its magnitude will depend on whether and how much we curb greenhouse gas emissions. Without a check on emissions, by the late 21st century some California regions could see warming of as much as five degrees Celsius, and more than 15 extreme fire weather days each autumn.

New reality of multiple, simultaneous fire incidents

The motivation for the study was the dual fire disasters that unfolded in November 2018, when the deadly Camp Fire raced through the northern Sierra foothills and the town of Paradise, and the Woolsey Fire tore a destructive path across the Santa Monica Mountains in Malibu.

These prolonged, simultaneous events placed substantial burdens on firefighters and communities. Now this is playing out again, except on a larger scale, with firefighters stretched to the limit. According to Cal Fire, 14,000 firefighters are on duty across the state, battling 25 large wildfires.

“Humans are ingenious at managing climate risk, but our systems are built around the historical climate,” Diffenbaugh said. “Systems that were built for the old climate are being stressed in a new way.”

Wildfires have fundamentally changed, but the way we prepare for and manage them has not.

“Managing wildfires in California in a disruptive climate scenario is possible but not simple,” Carvalho said. “Fire management strategies can help but cannot solve the impact of an increase in the frequency and intensity of extreme events, and the consequent disruption of multiple disasters, such as the ones we have observed recently.”

The unprecedented fires this year illustrate the difficulty of adapting as climate goal posts shift.

Diffenbaugh said there is clear evidence that we should be expecting events that fall outside our historical experience. “We’re not yet adapted to the climate change that has already happened, so becoming resilient will require catching up to that change and getting ahead of the global warming that will happen in the future,” he said.

Jason Samenow contributed to this report.