Update: Frontier Fire in Siskiyou County remains at 50% containment as of Monday evening

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Updated: 6:17 p.m. May 18

First discovered: 2 hours ago, 3:59 p.m. May 18

Initial location: Harry Cash Rd -Cross of Frontier Dr. Montague, Siskiyou County, Calif.

Fire unit: Cal Fire Siskiyou Unit

Fire type: Wildfire

Fire name: Frontier Fire

Frontier Fire initially started today at 3:59 p.m. at Harry Cash Rd -Cross of Frontier Dr. Montague in Siskiyou County, California.

It has burned 22.3 acres after being active for two hours. A fire crew of 90 has been working on site and, by Monday evening, they managed to contain 50% of the fire. Investigations into its cause are still ongoing.

Nine engines, two water tenders, three helicopters, one dozer and two hand crews are working to control the fire. According to Cal Fire, "Numerous firefighting air tankers from throughout the State are flying fire suppression missions as conditions allow."

Fire containment

This is what 50% containment means

Containment indicates what percentage of the fire perimeter has been surrounded by a control line. In this case, it means that 50% of the wildfire is contained from spreading, while 50% is still uncontrolled.

Containment is part of a larger plan for managing a wildfire. It is normally expressed as a percentage and it refers to how much of the fire perimeter has been surrounded/enclosed by a control line that firefighters create. The containment percentage indicates a certain level of control, but it doesn't always correlate to safety level. Also, it's important to note that containment doesn't mean a fire is out.

How is containment measured?

The incident's central command constantly receives progress reports from firefighters on the ground. As the fireline is constructed, inspected or reinforced, mappers record those details to adjust the containment percentage. The percentage tells the public how much of the fire perimeter is believed to not go beyond the control lines.

Source: Cal Fire

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This story was originally published May 18, 2026 at 4:37 PM.