Fire managers across the south-west are reckoning with strong winds that forecasters say could lead to explosive growth in wildfires this week.
Hundreds of people were moved to safety in blazes that have scorched buildings and signalled an early start to the fire season.
A wildfire on the outskirts of Flagstaff, Arizona, on Wednesday continued its run though dry grass and scattered pines around homes into volcanic cinder fields, where roots underground can ignite and send small rocks flying into the air, fire officials said.
Aircraft were grounded for a second day because of high winds, and a major northern Arizona motorway remained closed as smoke shrouded the air.
Winds were expected to intensify Thursday after easing up on Wednesday.
There is some chance of rain on Friday but even stronger winds, followed by a dry forecast into next week, said Brian Klimowski of the National Weather Service.
“Folks, we have entered our fire season," Mr Klimowski said. “It’s going to be a long one this year.”
At a community meeting in Flagstaff, residents questioned how a small blaze reported north-east of the city on Sunday afternoon grew to more than 77 square kilometres by Wednesday afternoon.
The cause of the fire is under investigation. Firefighters have yet to contain any part of it.
Hundreds of people have been moved to safety in Arizona and New Mexico because of wildfires.
In New Mexico, the Mora County Sheriff's Office expanded evacuation orders as winds fuelled a 36 square-kilometre blaze.
A new fire emerged on Wednesday in a wooded area along the Rio Grande, south of Albuquerque.
In Colorado, new wildfires prompted evacuations in Monte Vista, a city of about 4,150 people in the southern part of the state, and near Longmont.
An undetermined number of buildings were burnt but no one was injured, authorities said.
The number of hectacres burned in the US so far this year is about 30 per cent above the 10-year average.
Above-average temperatures and below-average rain have combined with spring winds to raise the risk of catastrophic fires.
On the outskirts of Flagstaff, where tourists and locals revel in hiking and horseback riding trails, camping spots, and the vast expanse of cinder fields for off-road vehicle use, flames soared as high as 30 metres at times.
About 200 residents attended the community meeting on Wednesday in Flagstaff at a middle school that is also being used as a shelter.
Some lost their homes and were worried about finding temporary housing in a city where rental prices have exploded in recent years.
Coconino County officials told residents of a system set up to offer assistance. Sheriff Jim Driscoll could not say when residents might be allowed back home. About 765 houses were evacuated.
“There’s still active firefighting going on in those areas and we need to have it safe for you to go in,” Mr Driscoll said.
Lisa Wells is among the residents whose home was burnt. She said she saw a puff of smoke outside her window on Tuesday.
Before long, the smoke blackened, the wind gained strength and entire trees were being consumed by flames.
In what felt like seconds, her family moved from being ready to go to fleeing.
Ms Wells grabbed medication and the family moved themselves, their alpacas, horses and dogs to safety, but left some animals behind.
“It was a miracle that people got out because we had so little time,” she said.
Birds, goats and chickens they left behind did not survive the fire. The family are staying at a hotel where their dogs also are welcome.
