TL;DR: Households one mile south and east of the Lucas Fire near Potter Valley were under evacuation orders on Sept. 13, 2026, while areas one mile north and west were under evacuation warnings, with the Lake County Fairgrounds at 401 Martin St. in Lakeport open as the evacuation shelter.

Fire location and size on Sept. 13

The Lucas Fire was burning in the Potter Valley area in Mendocino County near the Mendocino-Lake county line, according to Cal Fire as reported by KCRA.

The fire started Thursday afternoon southeast of Potter Valley near the Lake County-Mendocino County line, according to an update from Cal Fire reported by CBS San Francisco.

According to an update from Cal Fire reported by CBS San Francisco, the fire burned 4,109 acres as of about 7:15 p.m. on September 13, 2026, with containment at 25%.

KCRA reported that Cal Fire placed the burned area at at least 4,128 acres with 30% containment lines around the burn area in reporting updated at 8:52 p.m. PDT on Sept. 13, 2026, referencing a 7:02 a.m. Monday update.

Firefighters continued to increase containment on the fire burning near the Mendocino National Forest as evacuations remained in effect Sunday, according to CBS San Francisco in an update published September 13, 2026 at 7:15 p.m. PDT.

Officials said in a statement that a surge of resources into the area allowed crews to directly engage the fire while continuing to construct and reinforce containment lines, according to CBS San Francisco.

Officials also said cooler temperatures and lighter winds provided more favorable conditions and helped crews make significant progress, according to CBS San Francisco.

Why this fire moved quickly

The Lucas Fire began Thursday morning in Potter Valley in Mendocino County and crossed into Lake County on Thursday night, according to Lake County News.

It was impacting the Mendocino National Forest and Bachelor Valley area of Upper Lake, according to Lake County News.

In an update Sunday afternoon, officials noted the Lucas Fire was located in the burn scar of the 2018 Ranch Fire, part of the massive Mendocino Complex Fire that burned more than 400,000 acres that year, according to CBS San Francisco.

Cal Fire said the Lucas Fire was the 10th fire this decade to surpass 1,000 acres in the Sonoma-Lake-Napa Unit and was the largest in that area this year, according to KCRA.

CBS San Francisco also described the Lucas Fire as currently the largest wildfire burning in the Cal Fire Sonoma-Lake-Napa Unit this year.

On Friday, firefighters faced high temperatures and strong winds on the fire line, with resources to continue working overnight to gain additional containment and strengthen suppression efforts, according to Lake County News.

Five night-time helicopters were flying over the fire on Friday evening, officials said, according to Lake County News.

Cal Fire said 1,000 personnel were assigned to the incident as the fire grew from the 1,099 acres officials reported at the start of Friday to 3,466 acres by nightfall, with containment estimated at 10%, according to Lake County News.

What evacuation order and warning mean

Residents who lived one mile south and one mile east of the fire were under an evacuation order, according to KCRA.

An evacuation order means people need to immediately move out of the area due to an imminent threat, according to KCRA.

Evacuation warnings were issued for residents who lived one mile north and one mile west of the fire, according to KCRA.

Under an evacuation warning, residents were not required to leave home but should be prepared to do so, according to KCRA.

Those who needed additional time, including people with pets or livestock, should consider leaving now, according to KCRA.

Authorities urged residents to use caution around the incident and avoid unnecessary travel in areas under an evacuation warning, according to Lake County News.

Areas under an evacuation order remained closed, and residents should not attempt to re-enter until officials determined it was safe to do so, according to Lake County News.

Lake County evacuation orders in effect

Evacuation orders remained in effect for Lake County zones MNF-E016, MNF-E018, MNF-E019, UPP-E023, UPP-E025, UPP-E027 and UPP-E030, according to CBS San Francisco.

Lake County News listed the same Lake County order zones on Sept. 12, 2026, with the addition of UPP-E026, for a total of MNF-E016, MNF-E018, MNF-E019, UPP-E023, UPP-E025, UPP-E026, UPP-E027 and UPP-E030.

Residents can use zone numbers from the Lake County Sheriff's Office and Lake County Office of Emergency Services to identify whether an address falls inside an order or warning area.

Households should check the Genasys Protect emergency map used by Lake County for issuing mandatory evacuation orders and evacuation warnings.

The Lake County Sheriff's Office used zone numbers when sending evacuation orders, shelter-in-place warnings and other emergency information.

Mendocino County evacuation orders in effect

Evacuation orders were in effect for Mendocino County area MEN-2POT08-B, according to CBS San Francisco.

Mendocino County and its Office of Emergency Services, also known as MendoReady, used the Genasys Protect emergency map that included a grid of zones utilized for issuing mandatory evacuation orders and evacuation warnings.

Mendocino County officials recommended residents visit mendoready.org to receive public notifications from the Mendocino County Sheriff's Office about evacuation orders and warnings as well as shelters, road closures and more.

Residents can enhance disaster preparedness by identifying and integrating evacuation zone details into an emergency plan.

Households should enter an address into the search bar at the top left of the county evacuation zone map to determine the assigned zone.

Evacuation warnings for both counties

Areas under evacuation warning in Lake County were MNF-E012, MNF-E013, MNF-E015, MNF-E017, MNF-E021, UPP-E026, UPP-E028B, UPP-E032, UPP-E035 and UPP-E038, according to CBS San Francisco.

Mendocino County areas MEN-2POT08-A and MEN-2UKV28 were under evacuation warnings, according to CBS San Francisco.

Lake County News listed Lake County warning zones as MNF-E012, MNF-E013, MNF-E015, MNF-E017, MNF-E021, UPP-E028, UPP-E031, UPP-E032, UPP-E035 and UPP-E038.

Residents in areas under an evacuation warning should remain prepared to leave if conditions change, according to Lake County News.

Those who required additional time to evacuate, including residents with pets or livestock, should consider leaving early, according to Lake County News.

The National Weather Service on Friday issued a red flag warning for Lake County that was in effect from 10 a.m. Saturday to 2 a.m. Sunday due to forecast critical fire conditions including gusting northwest winds of 20 to 30 miles per hour and up to 40 miles per hour after higher ridges and lower humidity, according to Lake County News.

Where to go: Lake County Fairgrounds shelter

A temporary evacuation point was set up at Lake County Fairgrounds at 401 Martin Street in Lakeport, according to KCRA.

The evacuation point was also available for livestock, according to KCRA.

An official evacuation shelter staffed by the American Red Cross Northern California Chapter opened at 6 p.m. Friday in Fritch Hall at the Lake County Fairgrounds, 401 Martin St. in Lakeport, according to Lake County News.

Animal evacuation shelters were established at the Lake County Fairgrounds Baldwin Pavilion in Lakeport, according to CBS San Francisco.

Evacuees could enter the fairgrounds through the C Street gate or the main gate off Martin Street, according to Lake County News.

Parking was available behind Fritch Hall, according to Lake County News.

Residents were asked to keep vehicles clear of roadways within the fairgrounds to allow emergency and support vehicles to safely move throughout the property, according to Lake County News.

Bringing people, pets and livestock

Small animals were welcome but were housed in a separate area near Fritch Hall, according to Lake County News.

Livestock also were welcome at the fairgrounds, according to Lake County News.

Those bringing livestock to the facility were asked to enter through the livestock gate off Estep Drive, according to Lake County News.

Owners who evacuated animals to the Lake County Fairgrounds were responsible for their animals' ongoing care, according to Lake County News.

Evacuees should bring necessary medications, medical equipment and other essential items for themselves and their pets, according to Lake County News.

A shower trailer provided by the Sonoma County Department of Emergency Management was available onsite, according to Lake County News.

Road closures and forest closure

Traffic control points were established in the Upper Lake area to support evacuation and emergency response operations, according to Lake County News.

Those traffic control points were located at Highway 20 and Bachelor Valley Road, Highway 20 and Witter Springs Road, Highway 20 and Saratoga Springs Road, Elk Mountain Road and Pitney Lane, and Elk Mountain Road and CC Camp, according to Lake County News.

Motorists should avoid the affected area when possible and follow all directions from law enforcement and emergency personnel, according to Lake County News.

The U.S. Forest Service closed a portion of the Upper Lake Ranger District in the Mendocino National Forest in northern Lake County due to the fire, according to CBS San Francisco.

The closure impacted National Forest systems roads, trails and campgrounds, including Middle Creek, Penny Pines and Deer Valley, according to CBS San Francisco.

Local emergency and response coordination

On Friday, Lake County's sheriff declared a local emergency in response to the Lucas fire, which over the course of the day more than tripled in size, according to Lake County News.

Sheriff Lucas Bingham, serving as the county's director of emergency services, proclaimed the local emergency, according to Lake County News.

The Lake County Board of Supervisors would consider ratifying the proclamation when it met Tuesday, according to Lake County News.

The Lake County Emergency Operations Center remained activated, with county departments and response partners coordinating resources, monitoring changing conditions and supporting affected communities, according to Lake County News.

A joint information center was also established to coordinate public information related to the incident, according to Lake County News.

No injuries were reported, and the cause of the fire was under investigation, according to CBS San Francisco.

Sources referenced