The West is sizzling under extreme heat and bracing for the threat of more fires as thousands remain evacuated in California

(CNN) — The West is sizzling under a major, prolonged heatwave through July 4 and beyond that’s bringing triple-digit temperatures and fueling wildfire risk as thousands have had to flee their homes from an advancing Northern California blaze.

The Thompson Fire has consumed over 3,700 acres in California’s Butte County since it was reported Tuesday, drawing hundreds of firefighters to battle the flames under the extreme heat in the Oroville, California, area. As of Thursday morning, the fire is 7% contained, according to the California Department of Forestry and Fire Protection.

The fire has injured 11 firefighters, according to Chris Peterson, a California Fire spokesperson. Heat-related illnesses have affected eight firefighters, who have been evaluated and are in the process of being cleared, Peterson said.

Three other firefighters were hurt when a fire engine was involved in a rollover accident Wednesday morning, Peterson said. All three were taken to the hospital and two have since been released.

As of Thursday morning, 12,000 residents living in and around Oroville remain under evacuation orders, Peterson said.

At least four structures have been destroyed and more than 12,000 remain threatened by the fire, according to a Cal Fire incident update.

Oroville resident Rachael Thompson could see the flames and smoke from her backyard before she and three of her family members fled their home Tuesday night.

“It was a rough night for our family,” Thompson told CNN in a message. “The smoke in our home was incredibly bad even with 4 purifiers going.”

Though she has since received word that the fire has moved away from her home, she worries for her neighbors and friends, many of whom are displaced and don’t know if their homes are still standing.

“We hope our friends and family’s homes make it and that they’re all safe,” she said.

Californians are all too familiar with the sudden devastation that wildfires bring. The Thompson Fire is burning just 20 miles south of Paradise, where California’s deadliest wildfire killed 85 people and destroyed thousands of homes in 2018.

There are now over two dozen active wildfires of varying sizes burning across California, and the Thompson Fire is among the largest, according to Cal Fire.

“We’re seeing fires on the coast in San Diego, to the foothills in Butte,” Cal Fire Deputy Director Nick Schuler told CNN Wednesday. “Our firefighters are battling fires across California and often times on the line for more than 24 hours. It’s difficult conditions that they face.”

California Gov. Gavin Newsom declared a state of emergency for the area of the Thompson Fire Wednesday, clearing the path for additional resources, including the possibility of mobilizing the California National Guard to assist.

The state’s been seeing an active fire season, with 139,590 acres burned so far in 2024 compared to 7,812 acres burned by this time last year, according to Cal Fire.

“What we’ve seen so far in California – more than 600% increase in wildfires,” Schuler told CNN.

The extreme heat is combining with gusty winds and low humidity to set the stage for rapid fire spread through already parched vegetation, and it represents another obstacles for firefighters battling the blaze. Red flag warnings are in effect across the West, including in the Thompson Fire zone.

“This winter we enjoyed a lot of precipitation and that brought a lot of vegetation that was green just a few weeks ago,” Schuler said. “Now, with that heat increased temperatures drying out, resulting in rapid fire growth across the state.”

The Basin Fire in California’s Fresno County is 46% contained at 13,980 acres. Meanwhile, firefighters have the Fresno June Lightning Complex nearly fully contained to 10,669 acres.

“Firefighters are likely to have a very challenging week ahead,” Cal Fire officials said in a video update Tuesday. “All it takes is one spark to start a major wildfire putting lives at risk.”

Oroville will see record temperatures of 110 or more each of the next five days. Saturday may reach an all-time record high of 113 – making it that much harder for fire crews to fight the blaze.

No relief from the extreme heat for days

Record-breaking heat is making the Fourth of July week a dangerous one across much of the West and from the southern Plains to the Mid-Atlantic.

Nationwide, more than 140 million people across more than 20 states in parts of the South and West are under heat alerts – and there will be no relief until the middle of next week.

“The duration of this heat is also concerning as scorching above average temperatures are forecast to linger into next week,” the National Weather Service said. “Heat impacts can compound over time, therefore it is important to remain weather aware and follow the advice of local officials.”

Extreme heat is one of the leading weather-related killers in the United States, leaving hundreds of people dead each year, according to the National Weather Service.

Parts of Oregon will also experience triple digits Friday, and the heat could last up to five days with noted poor overnight relief, says the National Weather Service Portland.

Jessica Vega Pederson, chair of Multnomah Country, declared a state of emergency effective this weekend, noted a news release from the county Wednesday.

Multnomah County’s health officer, Dr. Richard Bruno, said in a news release: “I’m particularly worried about the thousands of people heading to music festivals and sporting events this weekend. They’ll be spending a long time outside, may have little access to shade and water and may not recognize the risk.”

Multnomah County is the state’s most populous county and home to Portland, where Mayor Ted Wheeler has also declared a state of emergency.

Starting Friday, the cities of Hood River, Portland and Salem are all forecast for temperatures of 100 Fahrenheit a five-day span, according to the National Weather Service. Eugene will face a four-day stretch of 100 Fahrenheit temps.

Noah Alviz, a meteorologist with the National Weather Service of Portland, told CNN via phone: “In June 2021, for a heatwave here in northwest Oregon and southwest Washington … Portland reached an all-time record of 116. Now, with this heatwave, we’re not expecting temperatures to get as intense as that. However, what we are more concerned about is the duration of this heatwave.”

During the summer of 2021, Multnomah County reported 72 heat deaths with “all but three of those deaths resulting from a single five-day heat wave in June,” according to the county.

“That is a big concern from us when we see heat of this magnitude in our area,” Alviz said.

There is the additional concern of staying cool in an area where many don’t have air conditioning, Alviz says, which has resulted in the opening of numerous cooling shelters in Multnomah County.

Meanwhile, much of California, excluding the coastal regions, as well as western Nevada and southwestern Arizona, are expected to see searing high temperatures from 100 to 110 degrees – about 10 to 20 degrees above normal.

Las Vegas, Nevada, could exceed its all-time high temperature of 117 degrees Sunday or Monday, and Death Valley, California, could approach 130 degrees by Sunday.

As the heat dome expands north, above-normal temperatures are expected to hit parts of Oregon and Washington beginning Friday, with high temperatures ranging between 95 to 105 degrees.

Some cities could swelter through multiple days of temperatures well above 100 degrees with some, including Sacramento, potentially seeing a full week of highs over 105 degrees.

Already, several cities have set or tied daily high-temperature records, with Fresno and Livermore both hitting 110 degrees Wednesday.

Heat is expected to spread to the Northwest and to parts of Arizona including Phoenix by the weekend, where triple-digit temperatures are expected, with parts of Arizona seeing highs above 110 degrees.