The surficial sediment strength of nearshore zone sands has previously been correlated to wave conditions in a qualitative manner. In this study, a coefficient of wave impact on sediment surface strength (CWS) is proposed to enable a quantitative assessment. The CWS was tested along a cross-shore transect in Duck, NC. The geotechnical input parameters for the CWS were measured using a portable free fall penetrometer. The offshore wavelength was extracted from a WaveRider buoy deployed in 17 m, and the water depth was derived from the penetrometer’s pressure transducer. The results showed that the CWS coefficient reflects the change in sediment strength with wave-seabed interaction. Along the profile, the CWS ranged from 0.005 to 1.627. The CWS slightly increased at water depths shallower than the depth of closure (∼4.5 m) and drastically increased at water depths shallower than breaker depth (∼2 m), reaching a maximum value of 1.6.