The largest wildfire in the US has torched more dry forest landscape in Oregon, one of dozens of major blazes burning across the west as critically dangerous fire weather looms in the coming days.
The destructive Bootleg Fire just north of the California border grew to more than 1210 square kilometres on Sunday.
Erratic winds fed the blaze, creating dangerous conditions for firefighters, said John Flannigan, an operations section chief on the 2000-person force battling the flames.
"Weather is really against us," he said. "It's going to be dry and air is going to be unstable."
Authorities expanded evacuations that now affect about 2000 residents of a largely rural area of lakes and wildlife refuges.
The blaze, which was 22 per cent contained, has burned at least 67 homes and 100 outbuildings while threatening thousands more.
US Fire Service battling 16 major blazes across the Pacific northwest
At the other end of the state, a fire in the mountains of northeast Oregon grew to more than 44 square kilometres by Sunday.
The Elbow Creek Fire that started on Thursday has prompted evacuations in several small, remote communities. It was 10 per cent contained.
In California, a growing wildfire south of Lake Tahoe jumped a highway, prompting more evacuation orders.
The Tamarack Fire, which was sparked by lightning on July 4, had charred nearly 74 sq km of dry brush and timber as of Sunday morning. It has destroyed at least two structures, authorities said.
Meteorologists predicted critically dangerous fire weather, with lightning possible through at least Monday in both California and southern Oregon.
Extremely dry conditions and heatwaves tied to climate change have swept the region, making wildfires harder to fight.
Northern California's Dixie Fire roared to new life on Sunday. The wildfire, near the 2018 site of the deadliest US blaze in recent memory, was 15 per cent contained and covered 100 sq km.
The fire is northeast of the town of Paradise, and survivors of that horrific fire that killed 85 people watched warily as the new blaze burned.
About 70 active large fires and complexes of multiple blazes have burned nearly 4300 sq km in the US, the National Interagency Fire Center said.
The US Forest Service said at least 16 major fires were burning in the Pacific northwest alone.
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