Surf forecasts are vital for safety, property protection, and planning of coastal activities. In Hawaii, surf is frequently dangerous during the boreal fall through spring for northwest- through north-facing coastal areas, which are characterized by narrow shelves, steep bottom slopes, and zones of high refraction. Forecasts of deepwater wave characteristics have improved with the advancement of the Wave Watch III model. A waverider buoy located 5 km northwest of Waimea Bay, Oahu measures the deepwater wave field. Although the offshore wave field is well forecasted and observed, the transformation to surf heights has not been clearly defined and verified. This paper describes an empirical method for estimating breaker heights derived from a comparison of Waimea buoy measurements and north shore, Oahu daily surf observations, which nominally represent the H_1/10 for the locations with the highest reported surf and have been recorded in Hawaii scale. The first task of this study is to translate the visual surf observations from Hawaii scale to trough-to-crest heights. The results show that the trough-to-crest heights are twice the Hawaii scale values within the 10–20% margin of error for the full range of breaker sizes encountered in Hawaii. The empirical method is resolved by deriving a coefficient of refraction on the basis of comparisons of the trough-to-crest surf observations with the shoaling-only, estimated breaker heights, which are calculated from the Waimea buoy's significant wave heights and dominant periods. The resultant formula uses offshore wave height and period to estimate surf heights, which represent the H_1/10 for zones of high refraction, i.e., nominally the areas of highest surf. The empirical formula should be applicable to other coastal zones of the world with similar geophysical traits and could serve as a scale reference for coastal wave models, such as the Simulating Waves Nearshore model.