 The road begins at a remote interchange with US 101 south of King City in the Salinas River Valley. Leaving US 101, SR 198 passes through the Priest Valley, climbs the Diablo Range as a two-lane road and crosses over an unnamed pass. It then descends along Warthan Canyon to the town of Coalinga in the agricultural Central Valley, where it briefly runs concurrently with SR 33. On both sides of Coalinga the road passes through the enormous Coalinga Oil Field.
