It happened around 3:30 Monday afternoon.
The California Highway Patrol says the 55-year-old was on Dickenson Ferry Road, west of El Capitan School Road when for an unknown reason, she drifted off the road causing her pickup to flip over.
Officers say she was not wearing her seatbelt and was ejected from the truck into a pole.
The woman died on scene.
Officers are asking anyone who may have seen the crash to contact them.