(AP) – Wildfires have expanded in areas of California’s wine country and Central Oregon overnight, leading to numerous evacuations. Firefighters were actively working on Sunday to contain these fires in the midst of hot and dry conditions.

The Pickett Fire located in Napa County expanded to over 10 square miles (26 square kilometers) and was reported to be 11% controlled by early Sunday, per the California Department of Forestry & Fire Protection.

Evacuations were ordered for approximately 190 individuals, with evacuation warnings issued for around 360 more, as the fire posed a threat to about 500 buildings near Aetna Springs and Pope Valley, according to Jason Clay, a spokesperson for Calfire Sonoma Lake-Napa Unit.

Over 1,230 firefighters, along with support from 10 helicopters, were engaged in combating the blaze, which started on Thursday following a period of intense heat. The origin of the fire is still being investigated.

Residents across the Western United States have been enduring a heatwave that has led to hospital admissions for some, with dangerously high temperatures expected over the weekend in Washington, Oregon, Southern California, Nevada, and Arizona.

Clay noted that while weather conditions have somewhat eased since the fire began, Sunday’s temperature was expected to reach 94 degrees (34 Celsius). However, humidity was predicted to decrease, and wind activity was likely to increase later in the afternoon.

“That’s been a driving factor in the afternoons since we’ve seen the fire activity pick up for the last three days,” Clay said, adding that “support from all up and down California has been critical to our efforts.”

The fire began in the same area as the much larger Glass Fire in 2020, which crossed into Sonoma County and eventually burned about 105 square miles (272 square kilometers) and more than 1,500 structures.

That fire was driven by wind, while the current fire is fueled by dry vegetation on steep slopes — some of it dead and downed trees left over from the Glass Fire and some of it grass and brush that grew back and then dried out again, said Clay.

In Oregon, the Flat Fire in Deschutes and Jefferson counties had grown to almost 34 square miles (88 square kilometers), with no containment, and threatened nearly 4,000 homes, according to the state Fire Marshal’s Office. About 10,000 people were under some sort of evacuation notice.

The fire began Thursday night and grew quickly amid hot, gusty conditions. Fire officials were keeping an eye on isolated thunderstorms in Southern Oregon that could drift north on Sunday, spokesman Chris Schimmer said in a video posted to Facebook.

Although it’s difficult to directly tie a single fire or weather event directly to climate change, scientists say human-caused warming from burning fossil fuels like coal and gas is causing more intense heat waves and droughts, which in turn set the stage for more destructive wildfires.