Buoywatch
Both point to where they come from
On a buoy report, wave direction and wind direction use the same convention: the direction they are coming from, in degrees clockwise from true north. NOAA’s National Data Buoy Center defines mean wave direction as the direction from which the waves at the dominant period are coming, and wind direction as the direction the wind is coming from. So a 315° swell comes from the north-west, and a 90° wind blows from the east.
Reading the degrees
0° (or 360°) is north, 90° east, 180° south and 270° west. Buoywatch also shows the compass point, such as NW or WNW, next to the degrees. Each of the 16 compass points covers 22.5°.
Swell direction: will it reach you?
Swell direction tells you whether waves can reach your break. A beach facing west, such as Ocean Beach in San Francisco, is open to north-west and west swells. Oahu’s North Shore lights up on north-west and north swells, and is largely sheltered from south swells, which favour the South Shore instead. Headlands and islands can block some directions completely.
Wind direction: how clean will it be?
Wind matters relative to the shape of your coast. Offshore wind blows from the land out to sea and tends to groom the waves, holding them up. Onshore wind blows from the sea onto the beach and makes the surface choppy. On a west-facing California beach, an east wind is offshore; on Oahu’s North Shore, the usual north-east trade winds blow cross- to onshore, which is why light-wind days are prized there.
Putting them together
A good day usually needs both: a swell from a direction your spot is open to, and light or offshore wind. Check both on the buoy report, then the tide.
