The woman, Sarani Banerjee, 49, from Howrah, India, was in the back seat of a Toyota Camry heading northbound on Skyline Boulevard about a half-mile south of Old La Honda Road just before 7 p.m., CHP Officer Art Montiel said.
Driving the car was her son, Shamik Banerjee, 31, of Mountain View. His father, Kalyan Banerjee, 61, was in the front passenger seat, Mr. Montiel said.
The Camry was negotiating a curve when it was driven off the road onto a dirt and gravel shoulder, Mr. Montiel said.
When the car returned to the road, it collided head-on with a Chevrolet Monte Carlo driven by Susan Michele Cozad, 58, from Nice, California, near Clear Lake.
The Camry flipped and came to rest on its roof.
Ms. Banerjee was pronounced dead at the scene. Her husband was transported by helicopter to Stanford Hospital with major injuries.
Her son was also taken to the hospital. He suffered no injuries, Mr. Montiel said.
Ms. Cozad, the Monte Carlo's sole occupant, was not injured in the crash, Mr. Montiel said.
The roadway was closed for about four hours after the fatal crash.
The cause of the crash is under investigation, according to the CHP.
"At this point, we're just trying to figure out why he went off the road," Mr. Montiel said.
— Bay City News Service and the Almanac