LAS VEGAS, N.M. (AP) -- Dangerous, gusty winds were expected to continue Monday across northeast New Mexico, complicating the fight against wildfires that threaten thousands of homes in mountainous rural communities.
The region's largest city -- Las Vegas, New Mexico, home to 13,000 people -- was largely safe from danger after firefighters mostly stopped a blaze there from moving east. But the northern and southern flanks of the wildfire proved trickier to contain as wind gusts topped 50 mph (80 kph).
"It's been a challenging day. The winds have picked up; they haven't let up," fire spokesperson Todd Abel said Sunday night.
A so-called "red flag warning" that indicates high fire danger due to heat, low humidity and fast winds will remain in place through Monday night, nearly four days after it began.
More than 1,600 firefighters were out Sunday battling the two major blazes burning northeast of Santa Fe, New Mexico. Together they covered 275 square miles (some 710 square kilometers), an area more than twice the size of Philadelphia. Firefighters had contained nearly half of the blazes by Sunday night.
Still, the threat was far from over with the National Interagency Fire Center saying early Sunday that more than 20,000 structures remained threatened by the fire, which has destroyed about 300 residences over the past two weeks.
Fast winds are in many ways firefighters' worst nightmare, especially in conditions as hot and dry as those the crews have been battling in the Southwest since early April.
In addition to fanning and spreading the flames, these winds keep air tankers and light planes grounded. That left them unable to drop water directly on the fire or lay down retardant ahead of its path to allow bulldozers and ground crews to dig firebreaks in places where there are no highways or roads to help stop the progression.
In extreme conditions, like the ones in New Mexico, even the helicopters that can typically get up in the air --- at least during the early morning hours before winds start to pick up in the afternoon --- are grounded. That prevents them from gathering intelligence about overnight developments. Aircraft were able to fly early Sunday but were grounded by the afternoon.
"It's not good, obviously; it takes away a tool in our toolbox, but we're not stopping," said fire spokesperson Ryan Berlin.
Officials were concerned about winds that had whipped up more flames on the northern edge of the fire near some very small communities of several hundred people. Gusts had driven fire down into a canyon, making it difficult to get to, said Dave Bales, the incident commander.
He and other officials strongly urged people to be ready to evacuate or to leave immediately if they've been told to do so. Should the fire overwhelm a community, heavy smoke and congested roads could make it hard for people to flee and for firefighters to access the area, he said.
"It is so thick you can't see, you can't drive, you can't see the engine ahead of you," Bales said.
Those towns sit along a state highway that runs from Las Vegas, New Mexico, up to Taos, a popular place for skiing and other outdoor recreation. Taos, however, was not threatened, but people in some parts of the larger Taos County have been told to prepare for possible evacuations.
In the small community of Las Vegas, some residents began returning on Saturday and some local businesses reopened. Containment lines established by bulldozers as well as the direction of the wind helped keep the community safe over the weekend. But some fire officials warned people to remain aware of evacuation orders because conditions could change quickly.
"Just because the winds are coming from one direction doesn't mean they can't change direction, so it's better to be prepared and have residents ready to go," said Wendy Mason with the New Mexico Forestry Division.
Nationwide, close to 2,000 square miles (5,180 square kilometers) have burned so far this year, with 2018 being the last time this much fire had been reported at this point, according to the National Interagency Fire Center. And predictions for the rest of the spring do not bode well for the West, where long-term drought and warmer temperatures brought on by climate change have combined to worsen the threat of wildfire.