UPDATE 7/15/17 3:37 p.m.: CHP San Luis Obispo reports as of 2:50 p.m., all lanes of Hwy. 101 northbound are open and the fire is extinguished.
UPDATE 7/15/17 9:37 a.m.: Cal Fire says the forward progress of what's being called the Grade Fire has stopped. "Fire is holding to retardant lines and mid slope road. Crews working on hot spots and containment," the agency says in a tweet.
A 15-acre grass fire is burning Saturday morning on the Cuesta Grade, adjacent to northbound Highway 101 in San Luis Obispo County. San Luis Obispo county and city fire companies are on the scene.
CalTrans has closed two of the three northbound lanes, so traffic on that stretch is expected to be heavy this morning.
Cal Fire San Luis Obispo said the fire is "burning uphill against the wind," but that crews are making good progress.
We'll update this post as more information becomes available.