It’s so dry in Bellingham, landscaping bark spontaneously combusted. Here’s what to know.

An “unusual” fire in the Geneva neighborhood should serve as a warning to all Whatcom County homeowners of just how dry the conditions are in the area as we move through the “dog days” of August.

At 6:12 p.m. Friday, South Whatcom Fire Authority and Bellingham Fire Department crews responded to reports of a structure fire at 2881 Lake Whatcom Blvd.

“The good news is it wasn’t anything big,” South Whatcom Fire Chief Dave Ralston said. “It was a residential fire that was alertly reported by a neighbor that saw some smoke from the back side of the house. The occupants were not home... it wasn’t anything all that interesting.”

But what did make it interesting, Ralston said, was how the fire ignited.

Ralston said the cause is suspected to be some decorative bark that apparently spontaneously combusted about a week after the owners had put it down.

“It’s rare, but it does happen,” Ralston said. “It’s more about a reaction from how the bark is mulched and processed. It sits for a time and starts building up heat, and it can start a fire.”

Ralston said heat can build up in mulch or bark, especially when it is in pile. If it gets hot enough and can get a source of oxygen, it could spark a flame.

“It just happens sometimes — not all that often, but it does happen,” Ralston said. “It depends on the type of wood chips, how they’re made, the amount of moisture in the area and the size of the pile. There’s no way to really prevent it from happening, other than to watch it. In this case, it happened in a naturally hot and dry area under an alcove.”

Fortunately, Friday’s fire only spread to the siding of the house and to a little bit of the substructure, Ralston said. He estimated the damage at “less than a couple thousand dollars.”

“They were real lucky they had such an observant neighbor,” Ralston said. “The owners actually arrived home when the fire department was still there and was concerned about what was going on. They were very thankful for their neighbors.

“It’s something we all just need to be aware of.”

Especially as temperatures in Bellingham are expected to reach the mid 80s this week, according to the National Weather Service Seattle office. Bellingham has not received any measurable rain since July 7 and got only 0.16 inches or precipitation in July — more than an inch below average.

With conditions so dry, Ralston said, “it’s never a bad idea” to keep mulch or bark moist.

“After you put water on it, take a rake and spread it around and look for smoke or steam,” he said.

Fireengineering.com also suggests:

▪ Keeping an eye on mulch beds in the afternoon when conditions are hotter and dryer.

▪ Not using mulch in areas anyone would smoke.

▪ Using a minimum 18-inch clearance between landscaped mulch beds and combustible building materials.

▪ Building proper clearance according to the manufacturer’s instructions between mulch beds and electrical devices, such as decorative lights. Also, use only the recommended size and wattage light bulbs in yard lights.

▪ Keeping mulch beds moist.

▪ Using non-combustible materials, such as rock or pea gravel around the gas meter and other combustible portions of a structure.

▪ Utilizing only electrical devices and cords listed for outdoor use.

▪ Consider replacing landscaping mulch with decorative stone.