Meredith Deliso, ABC News
(SANTA FE, N.M.) -- A massive wildfire currently burning east of Santa Fe, New Mexico, is now the largest in the state's history as thousands of firefighters continue to battle the blaze.
The Hermits Peak-Calf Canyon fire -- made up of two fires that merged into one giant blaze last month -- has burned 299,565 acres, state fire officials said Tuesday.
It officially surpassed the Whitewater-Baldy Fire as the largest fire in New Mexico's history on Monday. That fire, which was caused by lightning and also consisted of two separate fires that merged, had burned 297,845 acres primarily in the Gila National Forest before being contained in late July 2012.
The Hermits Peak-Calf Canyon fire, the largest active fire in the U.S., was only 26% contained as of Tuesday morning, with more than 2,090 fire personnel responding. The Hermits Peak fire was caused by spot fires from a prescribed burn, while the cause of the Calf Canyon fire is under investigation, according to state fire officials.
Residents of San Miguel, Mora, Taos and Colfax counties are advised to remain on "high alert" Tuesday for evacuation updates and road closures, officials said.
Firefighters faced unfavorable wind conditions, warming temperatures and severe dry conditions since the Hermits Peak and Calf Canyon fires ignited in early April.
"The challenge of predicting how wildfires move, the best experts in the world on this topic still are not going to get it right," Dr. Jason Knievel, deputy director for the National Center for Atmospheric Research, told Albuquerque ABC affiliate KOAT this week.
There is a mix of conifer trees, ponderosa pine, brush and grass where the fire is now -- and "critically dry fuels" may increase fire activity, fire officials warned Tuesday. The fire is burning near an area with steep terrain, which can also help spread the fire, according to Knievel.
"Fire tends to move uphill," he said.
New Mexico Gov. Michelle Lujan Grisham declared a state of emergency in several counties last month as multiple wildfires burned, including the Hermits Peak-Calf Canyon fire.
President Joe Biden approved a disaster declaration earlier this month for New Mexico that brings financial resources to the areas battling the fires.
Thousands of residents have been forced to evacuate and hundreds of structures have been destroyed due to the recent wildfire activity, the governor noted in a letter to Biden last week requesting additional aid.