Bobcat Fire: Blaze Grows To More Than 41K Acres; Firefighters Continue To Defend Mt. Wilson – LAist

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Jump to: Basics | Evacuations | Weather Conditions | About Mt. Wilson | Additional Resources

The Bobcat Fire continues to grow rapidly in the Angeles National Forest, causing evacuations and threatening foothill communities.

Last night, flames closed in on Mt. Wilson Observatory and firefighters were actively defending the facility. Officials said “favorable weather conditions” were helping crews as they worked overnight to protect the historic science station.

Here’s what we know about the fire so far today.


  • Acreage: 41,231 acres
  • Containment: 3% (the rate of fire growth Monday lowered total containment)
  • Resources deployed: 1,091 firefighters

The blaze erupted last Sunday near the Cogswell Dam and then spread rapidly amid an intense, record-breaking heat wave, prompting evacuation orders for Mt. Wilson Observatory. The cause is under investigation.

Firefighters continue to work in steep difficult terrain with help from helicopters and planes. Crews are hoping to take advantage of low winds forecasted for the next few days to build some containment lines around the flames.

The blaze continues to spread out of control, with spot fires breaking out and growing rapidly. Fire officials warned last night that resources to fight the fire were limited, which contributed to the fire’s growth “outpacing containment.”

“All critical thresholds for large fire growth are being met and exceeded,” fire officials wrote on the incident page. “[The f]ire is being influenced mostly by slope and fuel, so spread is likely in all directions.”

Firefighters actively defended the infrastructure at Mt. Wilson Observatory overnight, setting backfires on the slopes below the facility to slow the fire’s progression up to the peak. That accounted for a lot of the smoke and fire seen last night from below.

Crews continue to focus on that area this morning.

Residents of dozens of homes in the Sierra Madre / Arcadia area were ordered to evacuate Sunday, but firefighters have been able to keep the fire away from houses so far, officials say.

The fire was also burning into Spanish Canyon overnight, closing in on Monrovia Canyon Park. Monrovia city officials advised residents near the park to be ready to evacuate if needed, but that remains a warning as of Tuesday morning.


  • The Angeles National Forest — along with every other national forest in the state — has been closed through Sept. 21.
  • State Route 39 is closed at Old Gabriel Canyon Road to State Route 2
  • State Route 2 is closed from Upper Big Tujunga Canyon Road to Big Pines
  • Upper Big Tujunga Canyon Road
  • Mt. Wilson Road
  • Glendora Mountain Road
  • Glendora Ridge Road


The Bobcat Fire burns on hillsides behind homes in Arcadia on Sept. 13, 2020, prompting mandatory evacuations for residents of several communities living along the foothills of the San Gabriel Mountains. (Frederic J. Brown/AFP via Getty Images)


On Sunday morning, the city of Arcadia issued an evacuation order for all residents who live north of Elkins Avenue and east of Santa Anita Avenue. That area includes some homes in the adjacent city of Sierra Madre. That order remained in place Monday night, Arcadia city officials announced that afternoon.

An evacuation order is also in effect for Camp Williams, located just east of the burn zone in the Angeles National Forest.


Evacuation warnings remain in effect for the following foothill cities and communities:

  • Monrovia
  • Arcadia (excluding the neighborhood under mandatory evacuation orders)
  • Sierra Madre (except the 32 homes under mandatory evacuation orders)
  • Bradbury
  • Duarte
  • Pasadena
  • Altadena

“Residents should have evacuation plans in place, organize their emergency evacuation supplies, and have essential evacuation personal belongings easily accessible,” U.S. Forest Service officials wrote on the fire incident page. “Vehicles should be fully fueled, facing out in their driveways and ready to leave.”


A Red Cross Evacuation Center was re-established at Santa Anita Park, 285 W. Huntington Drive (entry at Gate 5).

L.A. County officials said a shelter site for horses has been established at the Pomona Fairplex (entry at Gate 12).


The South Coast Air Quality Management District extended a smoke advisory to Tuesday as unhealthy air continues to blanket much of the L.A. Basin and Inland Empire. It’s not just local fires though; smoke is also making its way to us from wildfires in Northern California, Oregon and Washington.

Smoke is expected to linger in the basin and valley areas, but officials say it will continue to clear up through this afternoon, thanks to south-blowing winds.

The unhealthy air prompted county officials to close three COVID-19 testing sites today:

  • Pomona Fairplex
  • San Gabriel Valley Airport
  • Panorama City

Look up the latest air quality info for your area at


Smoke rises behind Mt. Wilson Observatory as the Bobcat Fire burns in the Angeles National Forest on Sept. 14, 2020. (Mario Tama/Getty Images)

The Mt. Wilson Observatory houses 18 telescopes, many of which were used to make some of the greatest astronomical discoveries of the last century. They include the 100 inch Hooker telescope that Edwin Hubble used in the 1920s to prove that our universe is still expanding. Observatory Director Tom Meneghini said he’s afraid they could be seriously impacted if the fire gets close enough.

The heat can do irreparable damage. Our two big telescopes are historically significant and irreplaceable,” Meneghini said.

However, he said fires have gotten close before and the decades-old firefighting setup at the Observatory is ready to be used again. “We have an inground system of hoses and pumps,” he said.

“We have half a million gallons of water ready to pump so that’s all been prepared for any fire professional to come in and take over.”

The fire also threatens a seismic station that has recorded earthquake activity for 100 years, seismologist Lucy Jones said via Twitter.

Numerous television and radio stations have transmitters in the area, including our newsroom which broadcasts on the radio at 89.3 KPCC.


Ryan Fonseca and Sharon McNary are gathering updates on the fire.

This is a developing story. We fact check everything and rely only on information from credible sources (think fire, police, government officials and reporters on the ground). Sometimes, however, we make mistakes and/or initial reports turn out to be wrong. In all cases, we strive to bring you the most accurate information in real time and will update this story as new information becomes available.


For the latest information straight from local emergency officials, check the following websites and social media accounts:



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