Strong, fast winds complicated work for firefighters in northeast New Mexico on Sunday as they battled two major blazes, though the rural area’s major population center appeared to finally be safe from the worst danger.

“It’s been a challenging day. The winds have picked up; they haven’t let up,” fire spokesperson Todd Abel said Sunday evening.

The rural area’s largest town — Las Vegas, New Mexico, population 13,000 — sits on the eastern edge of the fire area and appeared safe for now thanks to fire lines dug with bulldozers and other preparations over the past week. But the northern and southern edges of the blaze were still proving tricky for firefighters to contain, particularly given winds as fast as 50 miles per hour (80 kilometers per hour), Abel said.

The fire’s perimeter stretched more than 60 miles (96 kilometers) from Las Vegas, New Mexico, on the southeast flank to near Holbrook about 50 miles (80 kilometers) south of the Colorado line. The National Interagency Fire Center said early Sunday that more than 20,000 structures remained threatened by the fire, which has destroyed about 300 residences over the last two weeks. The fire center said full containment wasn’t anticipated until the end of July.

The ferocious winds were expected to continue with little break Sunday night and at least into Monday. Strong, gusty winds are in many ways firefighters’ worst nightmare, especially in conditions so hot and dry as the crews in the Southwest have been battling since early April.

In addition to fanning and spreading the flames, such winds ground airtankers and light planes that can 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’s no highways or roads that can help stop the progression of the flames.

In extreme conditions, like the ones in New Mexico, even the helicopters that typically can get up in the air — at least during the early morning hours before winds start to pick up in the afternoon — are grounded. That means they’re unable to gather intelligence about the overnight developments critical to making new attack plans or placing new orders for firefighters, engines and more aircraft from across the region where demand grows exponentially as summer nears and the more traditional fire season begins.

Also Read: New Mexico residents brace for extreme wildfire conditions

Aircraft were able to fly early Sunday but were grounded by early afternoon, Abel said.

“It’s not good, obviously; it takes away a tool in our toolbox, but we’re not stopping,” said fire spokesperson Ryan Berlin.

Firefighters prepared to protect homes if needed in several other rural communities along the state highway that connects Las Vegas to Taos, a small community popular for outdoor recreation activities like skiing. Officials repeatedly urged people to evacuate if they have been told to do so.

“It’s a dogfight out there folks,” fire spokesperson Bill Morse said Sunday evening.

As of early Sunday, the biggest blaze northeast of Santa Fe had grown to an area more than twice the size of Philadelphia. Thousands of residents have been forced to flee their homes.

For now, the city of Las Vegas appears to be safe, said Berlin. Some residents of the area were able to return to their homes on Saturday, and some shops and restaurants had reopened.

“We even started to repopulate a section of town already,” he said. “Our concern right now is on the southwest portion of the fire which the wind is helping us out, sort of, because it’s blowing the flames back into the fire.”

But Wendy Mason with the New Mexico Forestry Division warned that “by no means” is anyone “out of potential danger.”

Also Read: Wildfires tear across several states, driven by high winds

“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,” she said.

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.