Data is collected related to a yaw-rate of a vehicle during a period of time. Based in part on the yaw-rate data, an actual trajectory and an ideal trajectory for the vehicle in the period of time are computed. A deviation of a yaw-rate associated with the actual trajectory is determined from a yaw-rate associated with the ideal trajectory. A variance of the deviation is calculated. An indication is provided of a dangerous driving condition if the variance exceeds a predetermined variance threshold.