ALBUQUERQUE, N.M. — A massive wildfire that has burned more than 265 square miles in the Gila National Forest has become the largest fire in New Mexico history, fire officials confirmed Wednesday.

The erratic blaze grew overnight to more than 170,000 acres, surpassing a blaze last year that burned 156,593 acres in Los Conchas and threatened the Los Alamos National Laboratory, the nation's premier nuclear facility.

And experts says the mammoth fire may be just a preview of what's to come in part of the western United States after months of drought and dry conditions.

The Gila forest fire also is the largest burning in the country. It formed last week when two lightning-sparked blazes merged in an isolated mountainous area in southwestern New Mexico, where it has destroyed about a dozen homes and prompted evacuations of nearby towns and health alerts for some of the state's largest cities.

Fire information officer Jerry Perry said about 1,200 firefighters from around the state were battling the growing blaze, but that they continue to face low humidity and shifting winds in their efforts.

"We still facing adverse weather conditions that are posing a challenge," Perry said. "We're doing a lot of burnout operations and yesterday we had to deal with a lot of spot fires."

The fire has not been contained, and officials worry that shifting winds and dryness related to the state's record drought may cause the blaze to grow even more.

The blaze so far has threatened few communities and was burning away from many of New Mexico's largest towns and cities. But state officials issued air quality alerts for cities as far as Albuquerque, nearly 170 miles away, and Santa Fe last weekend, and Perry said parts of southern New Mexico could expect to see smoke from the fire.

Jeremy Sullens, a wildland fire analyst at the National Interagency Fire Center, said La Nina is main reason the U.S. Southwest has experienced months of drought and saw a relatively mild winter. The grass that would have fallen because of snow remains high sparking more dangerous fire conditions, he said.

"It's highly likely that the western United States will see more fires this season that will that will require (out-of-state) resources to fight them," Sullens said.

He added July's monsoon season will probably help in alleviating some fires but it's unclear how much.

The National Weather Service said winds will likely blow smoke into Las Cruces on Wednesday and Thursday.

Officials said communities surrounding the fire area could expect smoke to linger into Thursday morning. Cold air after sundown will push warm air to the surface, trapping smoke closer to the ground.

The U.S. Forest Service reported Wednesday that crews were successful in protecting the small communities of Mogollon and Willow Creek, along with some private ranches and homes, with the help of burnout operations.

The two lightning-sparked fires that have burned for about two weeks merged amid strong winds to form the giant blaze, which has destroyed 12 cabins and seven small outbuildings. Windy conditions forced crews to the sidelines last week as the fire rapidly spread in an isolated area and charred homes in the community of Willow Creek, which remains under evacuation.

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Follow Russell Contreras on Twitter at http://twitter.com/russcontreras

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  • In this Tuesday, May 29, 2012 photo provided by the U.S. Forest Service, a firefighter walks along a burn out line as part of an effort to contain the nation's largest wildfire in the Gila National Forest in New Mexico. More than 1,200 firefighters are battling the blaze that has charred 340 square miles, or 218,000 acres, of terrain in the rugged mountains and canyons of southwestern New Mexico. (AP Photo/U.S. Forest Service, Mark Pater)

  • This Tuesday, May 22, 2012, photo, provided by David Thornburg shows a plume of smoke rising from the Whitewater fire burning in the Gila Wilderness east of Glenwood, N.M. Fire managers said the blaze had charred more than 10,000 acres before merging Wednesday afternoon with the nearby 11,500-acre Baldy fire. Both fires were sparked by lightning. (AP Photo/David Thornburg)

  • This May 29, 2012 photo provided by the US Forest Service Gila National Forest shows the massive blaze in the Gila National Forest, seen from Neighbors Mountain directly east of Glenwood, N.M. Fire officials said Wednesday May 30, 2012 the wildfire has burned more than 265 square miles has become the largest fire in New Mexico history. (AP Photo/US Forest Service)

  • This image provided by NASA shows smoke from New Mexico wildfires drifting across the southcentral United States. The image was acquired Thursday May 24, 2012 by NASA's MODIS satellite Aqua. Firefighters are battling a massive wildfire in southwestern New Mexico that has destroyed a dozen cabins and spread smoke across the state, prompting holiday weekend air-quality warnings. The fire burned early Saturday through remote and rugged terrain around the Gila Wilderness and has grown to 85,000 acres or more than 130 square miles. Fire officials say nearly all of the growth has come in recent days due to relentless winds. (AP Photo/NASA)

  • In this May 22, 2012 file photo provided by David Thornburg, a plume of smoke rises from the Whitewater fire burning in the Gila Wilderness east of Glenwood, N.M. Fire officials confirmed Wednesday, May 30, 2012, that the massive wildfire, which has burned more than 265 square miles in the Gila National Forest, has become the largest fire in New Mexico history. (AP Photo/David Thornburg, File)

  • This photo provided by InciWeb Incident Information System shows the Whitewater-Baldy Complex fire in Mogollon, N.M., a privately owned ghost town which was ordered to evacuate. Fire officials in New Mexico said Saturday, May 26, 2012, that the blaze has shrunk slightly to 82,000 acres but is still 0 percent contained because of weather conditions. (AP Photo/InciWeb Incident Information System)

  • Firefighters from the Granite Mountain Hotshots of Prescott, Ariz., cut a fire line along a mountain ridge outside Mogollon, N.M., on Saturday, June 2, 2012. The crew is part of an effort to manage and contain the Whitewater-Baldy fire which has burned more than 354 square miles of the Gila National Forest in New Mexico. (AP Photo/U.S. Forest Service, Tara Ross)