Surf heights are forecast heights of the face or front of waves. The surf forecast is based on the significant wave height, the average height of the one third largest waves, in the zone of maximum refraction. Some waves may be more than twice as high as the significant wave height. Expect to encounter rip currents in or near any surf zone.
I'm convinced visitors are oblivious to the danger of Hawaiian beaches. Almost all have rips and drownings are common. About once a month someone gets pounded to shreds on lava at places like Hanauma Bay .