A fast-moving brush fire burned hundreds of open acres in the far southeastern reaches of San Diego County Wednesday, prompting evacuation orders and shutting down a stretch of Interstate 8.
Crews worked on the ground and from the air in extreme heat to battle the Thorn Fire while CalFire officials said the blaze posed an “immediate threat to structures in the area.” Deputies evacuated nearby homes and businesses as a result.
The evacuation orders, which continued to expand as the fire grew rapidly in the evening, include areas north and south of I-8, bounded roughly on the west where Old Highway 80 meets I-8, extending to the northeast along Williams Road, and beyond McCain Valley Road to Tule Lake.
The temporary evacuation point is at Golden Acorn Casino, 1800 Golden Acorn Way in Campo.
Streets within the evacuation zone include Williams, Live Oaks Trail, Clements Street, High Pass Road, Lilac Lane, Manzanita and Cottonwood roads, Ribbonwood Boulevard, Ribbonwood Road, Angel Drive, Roadrunner Lane and Rocky Knoll Road.
In addition, some evacuation warnings were upgraded to orders, one to an area southeast of the fire zone, reaching state Route 94, and another farther east and north of I-8.
Other evacuation warnings have been issued, all to the north, approaching the Carrizo Gorge Wilderness Study Area, and northeast of the fire’s flashpoint along I-8.
The Thorn Fire, at 0% containment, was moving at a “moderate to dangerous rate of spread,” officials said. It had burned nearly 700 acres as of 6:40 p.m., well over double the area, 236 acres, that had been mapped an hour earlier, according to CalFire. The burn zone had been estimated at just 50 acres around 5 p.m.
Flames erupted for unknown reasons off Buckthorn Trail, south of I-8 and north of Campo Road in Boulevard around 3:30 p.m.
Within an hour, they had spread over about 30 open acres, CalFire reported, and evacuations, led by the San Diego County Sheriff’s Office, had begun.
A segment of I-8 in both directions is shut down near the burn area, according to Caltrans. Eastbound lanes close at Crestwood Road, and westbound, at SR-94/Ribbonwood Road. The closure, Caltrans said, will be “for an unknown duration.”
#ThornFire [update 5 p.m.] The fire is now 50 acres and has crossed Interstate 8 near Campo. There is an immediate threat to structures in the area. pic.twitter.com/GvIDAigFUl
— CAL FIRE/San Diego County Fire (@CALFIRESANDIEGO) July 16, 2026
There is also a smoke advisory for areas around Live Oak Springs, Boulevard, Tierra Del Sol and McCain Valley.
The region, meanwhile, is facing extreme temperatures, in the mid-90s to just over 100 degrees in the inland valleys and the mountains, and up to 113 in desert communities.
The National Weather Service issued an extreme-heat warning, which remains in effect until 8 p.m. Thursday.
#UPDATE @SDSheriff has updated the EVACUATION ORDER and EVACUATION WARNING due to changing conditions at the #ThornFire.
— San Diego Sheriff (@SDSheriff) July 16, 2026
An EVACUATION ORDER is in place for the shaded areas in red shown in the map below. It means everyone in the impacted areas must leave immediately.… pic.twitter.com/NFjWSqU0lX
City News Service contributed to this report.
Updated 7 p.m. July 15, 2026.
