LAKE COUNTY — The Lucas Fire expanded to 3,476 acres and reached 10 percent containment by Friday evening, prompting evacuation orders for approximately 2,000 residents in Lake and Mendocino Counties. An evacuation shelter opened at 6 p.m. Friday at Fritch Hall, Lake County Fairgrounds, located at 401 Martin Street in Lakeport.

The fire ignited at approximately 9:18 a.m. Thursday in an area of grass and oak trees near Potter Valley in Mendocino County. The blaze was located three miles east of State Route 20, northeast of Ukiah and northwest of Clear Lake.

Initial growth was rapid, with the fire reaching 10 acres initially before expanding to 40 acres by approximately 3 p.m. Thursday. It grew to 200 acres by 3:30 p.m. and reached 400 acres just after 4 p.m. on Thursday. By Friday morning, the Lucas Fire had burned over 1,000 acres and was 5 percent contained.

Evacuation warnings were issued for residents living one mile north and one mile west of the fire. Structures were immediately threatened in the vicinity of Bachelor Valley.

Specific zones were placed under mandatory evacuation orders, including Lake County zones MNF-E016, MNF-E018, MNF-E019, UPP-E023, UPP-E025, UPP-E026, UPP-E027, and UPP-E030. Mendocino County zone MEN-2POT08-B was also under evacuation orders. Evacuation warnings remained in effect for Lake County zones MNF-E012, MNF-E013, MNF-E015, MNF-E017, MNF-E021, UPP-E028, UPP-E031, UPP-E032, UPP-E035, and UPP-E038, as well as Mendocino County zones MEN-2POT08-A and MEN-2UKV28.

The evacuation shelter at the fairgrounds was staffed by the American Red Cross Northern California Chapter. Small animals were accepted at the fairgrounds in a separate area, while livestock evacuees were instructed to enter through the livestock gate off Estep Drive. Evacuees could enter the fairgrounds through the C Street gate or the main gate off Martin Street, with parking available behind Fritch Hall.

Several temporary traffic control points were active along Highway 20 to manage the flow of vehicles. The U.S. Forest Service issued an emergency closure for part of the Upper Lake Ranger District in the Mendocino National Forest. This closure includes forest roads, trails, and campgrounds such as Middle Creek, Penny Pines, and Deer Valley, as well as several off-highway vehicle trails.

Cal Fire stated that firefighters faced high temperatures and strong winds on the fire line Friday. Five night-flying helicopters were expected to work overnight to support suppression efforts. The agency said additional resources were arriving to assist with the Lucas Fire incident.

The cause of the Lucas Fire remained under investigation. Cal Fire confirmed lightning was recorded in the area on the morning of September 10, 2026. The Lucas Fire comes a day after the Steele Fire ignited in a burn scar near Lake Berryessa in Napa County.

Cal Fire said smoke from the Lucas Fire may affect air quality in Lake County and nearby communities. The National Weather Service issued a red flag warning for Lake County from 10 a.m. Saturday to 2 a.m. Sunday. The agency warned that gusty winds and low humidity could create critical fire weather conditions.

Why It Matters

The rapid expansion of the Lucas Fire, which grew from 10 acres to over 3,400 acres in less than two days, demonstrates the volatility of fire behavior in the region. The activation of evacuation orders and warnings affecting some 2,000 people reflects the immediate threat to residential areas and the necessity of coordinated emergency response across county lines.

The occurrence of the Lucas Fire shortly after the ignition of the Steele Fire in Napa County shows a period of heightened fire activity in Northern California. The implementation of emergency closures by the U.S. Forest Service and the issuance of red flag warnings by the National Weather Service reflect the broader public safety measures required to manage these concurrent incidents.

What's New

Additional reporting confirms that evacuation orders were in effect for Mendocino County zone MEN-2POT08-B. Evacuation warnings were also in effect for Mendocino County zones MEN-2POT08-A and MEN-2UKV28. According to Cal Fire, the cause of the Lucas Fire is under investigation.

Earlier data indicated the Lucas Fire was 5 percent contained as of Friday morning. Evacuation orders were in effect for Lake County zones MNF-E016, MNF-E018, MNF-E019, UPP-E023, UPP-E025, UPP-E026, UPP-E027, and UPP-E030. Reports state that evacuation orders and warnings affected some 2,000 people.

How Sources Differ

Reports differ on the containment percentage of the Lucas Fire. The Cal Fire Sonoma-Lake-Napa Unit incident report stated the fire was 10 percent contained as of 5:55 p.m. Friday.