The Madre Fire has grown above 70,800 acres as winds and plenty of tall, dry vegetation continue to feed the flames in southeastern San Luis Obispo County.

The blaze ignited around 1 p.m. Wednesday off Highway 166, about 40 miles northeast of Santa Maria and near the border between San Luis Obispo and Santa Barbara counties.

As of Friday, the fire continued expanding to the east-northeast onto the Carrizo Plains.

Due to the fire and large amount of firefighting equipment, two-lane Highway 166 connecting the Central Coast and the Cuyama Valley has remained closed since Wednesday, with no estimates for reopening.

Containment stood at 10% as of mid-day Friday.

One outbuilding was reported destroyed. Authorities estimated the fire threatened some 50 buildings.

Incident commanders have not  released an estimate for when the fire might be fully surrounded, not a surprise considering their descriptions of conditions include “excessive” and “challenging.” 

“The fire remained active throughout the night, displaying wind-driven runs and active fire behavior when topography and fuels align,” federal officials said.

Fueling the flames are short grasses about a foot tall, grasses about 2.5 feet tall, and chaparral up to 6 feet high.

Incident commanders expect fire behavior to continue to be extreme for the next 72 hours. 

“The presence of dry, cured annual grasses will support high rates of spread with intense flame lengths. Alignment of slope and wind will further exacerbate fire behavior, creating challenging suppression conditions,” according to the outlook.

The fire is burning in southeastern San Luis Obispo County, but within federal jurisdiction.

The area last burned more than 30 years ago, said Philip Oviatt, district public affairs manager for the Bureau of Land Management.

“It’s been awhile,” Oviatt added.

Fire can be a double-edge sword as flames racing across the landscape also can help get rid of invasive plants and grasses while also aiding with germination. 

“It’s proven to be beneficial to a lot of our wildflowers,” Oviatt said. 

Depending on how hot the fire burned and the upcoming rainy season ahead, this month’s burned land could deliver a colorful reward in the spring.

“It could actually help make a better bloom this next year,” Oviatt said. 

The cause of the Madre Fire remained under investigation.

The force fighting the fire doubled overnight with more than 600 personnel now involved. 

The incident command post and base camp have been established at the Santa Maria Elks/Unocal Event Center.

The team transitioned to unified command involving the U.S. Forest Service, Bureau of Land Management and Cal Fire as of Friday.

The Carrizo Plain National Monument, which sits in both San Luis Obispo and Kern counties, has been closed to public access for safety reasons, according to the Bureau of Land Management.

Representatives of the Santa Maria Speedway between Santa Mara and Nipomo said this weekend’s race will continue as planned.

“While the Madre Fire continues to impact our community, we wanted to let y’all know that the races for this Saturday, July 5th are still on,” Speedway representatives posted on social media.

“Our hearts are with those affected by the fire, and we send our deepest gratitude to the brave firefighters and first responders working tirelessly to protect our homes and the land

For details and tickets go to www.santamariaspeedway.net.

Information about evacuation orders and warnings can be found at readyslo.org and readysb.org